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CPU Air Cooler Roundup: Six Coolers from Noctua, SilverStone, be quiet!, and Cooler Masterby Dustin Sklavos on 3/14/2013 2:40 AM EST
- Posted in
- Cases/Cooling/PSUs
- Cooler Master
- SilverStone
- cooling
- Noctua
- be
63 Comments
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cjs150 - Thursday, March 14, 2013 - linkPersonally I would also prefer water cooling for the simple reason that a good (thick) 240/280 Radiator can cool both CPU and GPU and there is no need to worry about whether the RAM heatspreaders are too tall for the air cooler.
What the result show is just how good the closed loop water coolers have become.
However, there is no denying air cooling is simpler, less prone to messy accidents (I know!) and perfect for those who like to keep the computer on all the time. Nice review and keep up the good work Reply
James086 - Friday, March 15, 2013 - linkA minor caveat: be sure to point a fan at the ram and motherboard heatsinks. I didn't and because there was no airflow around my motherboard, it popped a VRM. Reply
StevoLincolnite - Monday, March 18, 2013 - linkRam cooling isn't important, they don't even need heatsinks, it's all for looks.
However, motherboard cooling is important, spend a little extra and get a motherboard with decent heatsinks or even active cooling like the Sabertooth x79.
Plus, case airflow is important too. Reply
maximumGPU - Thursday, March 14, 2013 - linkNice review! wish there was a thermalright silver arrow on there to get a more comprehensive look at the high end coolers. When i bought mine it was widely considered superior to closed loops, looking at the review's results i'm not so sure about that now. Reply
wiyosaya - Tuesday, April 02, 2013 - linkI've been a fan, pun intended, of Thermalright paired with Scythe fans for a long time. I currently have a TRUE Spirit 120M paired with a very low noise 120mm Scythe fan cooling an i7-3820. The absence of noise was a prime factor for me, and I don't overclock because stability is also of prime concern for me. IMHO, this combination works very well.
I, too, would have loved to have seen any of the Thermalright heat sinks in this review. Reply
iTzSnypah - Thursday, March 14, 2013 - linkI don't believe that the case has adequate airflow. Reply
iTzSnypah - Thursday, March 14, 2013 - linkAlso there is a fault in your testing methodology. When you tested the CLC's you effectively increased the number of case fans, which would increase airflow and decrease load temps.
I suggest you retest, with the case always having 3 fans, 1 intake and 2 exhaust. Reply
FragKrag - Thursday, March 14, 2013 - linkI don't think the point here is to get a completely unbiased performance test, but rather test the coolers in a realistic environment Reply
dragosmp - Thursday, March 14, 2013 - linkThe thing is there's not more realistic not to have case fans than to have them. One may argue that it's more likely to encounter systems that have one/two exhaust fans than to have only one intake.
I'm suspicious of these results as most sites put aircoolers in a much better light and my own experience show it's a bad bad thing to remove rear fans.
In this setup aircloolers spit warm air that is hardly being channeled out by anything; the positive pressure generated by the front intake can be dissipated in many ways that don't move the warm air around the CPU zone. I've worked recently with a 600T, if the up/rear fans were slowed to 400RPM (so still working) with a CM 212+ @1200RPM and a email@example.com the CPU got toasted in games 80°C+ - running the fans @800RPM decreased the temp by some 20°C.
"I removed every case fan but the front intake, which I ran at 5V to prevent it from affecting acoustics while still providing adequate airflow." - how much airflow was there thru the fan-less rear exhausts? Reply
lever_age - Thursday, March 14, 2013 - linkRight, look at how restrictive the back panel looks. Some people with intake-heavy setups (and that would be a whole lot more than a single fan at 5V in a large case that's very far away from the CPU cooler) cut out the spot and use a wire grille instead, and remove slot covers.
If it weren't for some of the top venting, the air coolers would have been really suffocated. In that setup, there is a bias towards the CLCs because their fans are actually working close to the actual vents on the case, due to how everything is mounted and positioned.
If you're only testing down to 30 dB, you can easily run a few more decent-quality fans at some ~800 rpm and get some more reasonable airflow without really increasing the noise level measured. Reply
Touche - Thursday, March 14, 2013 - linkI agree. The test setup is bad and not representative of most real life configurations. So bad that the whole review is pointless. Reply
BrokenCrayons - Thursday, March 14, 2013 - linkI disagree. The coolers are measured under similar conditions and their performance in degress over ambient are listed. While seeing them in a real-world scenario might give you measurements that are more in line with a fully populated case, the variances introduced by the additional, unnecessary hardware might make it more difficult to get consistent, comparable results. I'm more concerned about relative performance and how coolers stack against one another and Anandtech's testing methods appear to be the best way to obtain those results without unreasonable expectations about controlled environment facilities.
-BC Reply
lever_age - Thursday, March 14, 2013 - linkConsistency and simplicity are good, but a procedure with a significant inherent bias is not (especially if this detail is not discussed by the reviewer... when it is not, it frankly seems like shortsightedness or incompetence, if not something worse). I rarely complain about testing procedures on most reputable review sites, but something is obviously flawed here. The results, which are out of line with most others', seem to indicate problems as well.
There is nothing much that similar about how the air coolers and CLCs are being tested. The air coolers are being tested inside a relatively restricted box. The side-blowing towers are blowing towards a metal wall with some puncture holes from where the fan should be (also note the offset between holes and cooler, exacerbated by using a miniITX motherboard with socket unusually low). The CLCs are being tested with radiators and fans actually up against the openings in the chassis.
Actually, for that matter, it would be good to know exactly the orientation and placement of the radiators and fans for how the CLCs were tested.
Anyway, if you want a simplified setup, something more fair would be to just use an open-air test bench or no chassis at all. Reply
Touche - Friday, March 15, 2013 - linkI was about to reply to BrokenCrayons, but you summed it up pretty well. Reply
BrokenCrayons - Friday, March 15, 2013 - linkAn open air or open frame case might be a reasonable option. I hadn't really thought much about it and that's not a bad point. However, the net results -- the coolers in question all being tested in the same container -- would be the same. Honesty, Dustin could have stuffed all the hardware in a Tupperware container or a shoebox that used to have a pair of Nine & Co. Drama Print Peep-Toe Pumps in them and, as long as they were all under the same conditions, the result would be just as valid. Cooler effectiveness is a relative scale thing anyway since the conditions in which each person will use them are going to be unique to them. So many factors (room location, case exposure to sunlight, time of day, relative humidity, where you put your US Robotics ISA 28.8 data/fax modem, the number of Quantum BigFoot hard drives you have, etc.) impact a processor's operating tempratures that the testing methodology is trivial to the process of judging coolers as long as it remains consistent.
Atop that, Intel ships perfectly usable coolers with their boxed processors. While I enjoy the reviews, if I want a faster CPU, I'll invest the extra $100 on a next-model-up CPU instead of a pointlessly chromed-out cooler or I'll wait until a faster CPU is brought to market or I'll just do something else with my computer. Obviously that's a personal preference and others might feel differently, but in the grand scheme of things, only a few people can be bothered to even care about the difference between a CLC, an aftermarket air cooler, and something that came out of the box or was included in it when the OEM put it together. Reply
lever_age - Friday, March 15, 2013 - linkWith regards to Intel's usable boxed cooler that's good enough for most people, I quite agree. However, they're not good enough for people who want to overclock significantly or want lower noise or temperatures or whatever; though the class of DIY builders who care about these things is small, they are relatively highly represented among AnandTech readers. Anyway, regardless of review subject material, if something's posted on AnandTech, it should be insightful and accurate, right?
As for the other paragraph, I think you're misunderstanding an important point here, maybe because nobody really stated it explicitly.
If you test different cooling designs in different test setups, the relative rankings will be different. That's why the test configuration is an important consideration. I'm not so concerned by the absolute numbers reported. Dustin used a test setup that very much does not represent what most people would be using, and this setup favors the CLCs over the air coolers. Someone not realizing this will read the results and think that CLCs have better performance relative to the air coolers than what you'd get in the real world in most case configurations. It's highly misleading.
Or at least, that's what I believe based on reading others' test results and based on my intuition on the subject. If Dustin could prove me wrong and alleviate these concerns by retesting just a couple coolers on a different setup, I would be very appreciative and would promptly tuck the tail between the legs and run off. Reply
lever_age - Friday, March 15, 2013 - link(continuing... sorry, no edit feature exists I think)
As an example of how test setup would affect results, consider two test setups:
A -- ATX-style case with strong front-to-back airflow, closed-off side panel with no mesh
B -- open-air test bench
Down-blowing CPU coolers would put up a better fight against side-blowing tower coolers in B than in A. Hopefully it is intuitive why. Reply
firstname.lastname@example.com - Saturday, March 16, 2013 - linkThen why'd you read the review? Reply
Tetracycloide - Sunday, March 17, 2013 - linkThis:
"the testing methodology is trivial to the process of judging coolers as long as it remains consistent."
Is only true as long as the coolers being tested are fundamentally similar. What you're saying is akin to claiming it's ok to test a custom water loop against an air tower without hooking the water loop up to the CPU block because "the conditions are the same." How is it a fair comparison if you're denying one solution's access to the medium by which it cools? Reply
Azethoth - Tuesday, October 22, 2013 - linkNo, you are missing the issue. Yes, you can see relative performance, but because of the test flaw you can only compare the air coolers to each other (accurately) and the water coolers only to each other but you have to keep in mind that their fans bias even their results yielding advantage to the CLC with the most airflow added by its radiator fans.
To make it fair, you can possibly move the radiator outside the case and maybe run it in a hotbox that matches the test case interior.
Still, I think the only fair comparison is to add fans to the air coolers to match the radiator coolers as mentioned above. So you test CLC + radiator taking up vent space vs air cooler + extra fan taking up that same vent space.
So in practice I would expect this test to show that CLC are amazing and top performers. We see this. In fact the results made me look at the test method to see if the CLC were even allowed to reach equilibrium or not they seemed so skewed.
So good test for comparing only CLC to each other, or only AC to each other. Sucks for determining the true champions though because AC got shafted. Reply
kmmatney - Saturday, March 16, 2013 - linkThe test setup was fine to me, and all coolers are measured under the same conditions, which is what is really important. I have an 212 EVO cooling a Core i5 running at 4.3 Ghz. I can't stand any noise, so only have a single case fan, running very slow. I've been thinking about moving my single exhaust fan to be an intake to get positive pressure. Reply
Egg - Thursday, March 14, 2013 - linkWhat about a test bench? I can see where Dustin is coming from regarding not wanting the case fans to affect the test result. Reply
JeBarr - Thursday, March 14, 2013 - linkquote " the NH-L12 stands to impress as potentially the most powerful downward-flow cooler on the market."
Correction: Noctua NH-C14 or Phanteks PH-TC14CS hold that title.
Thanks again Dustin for another fine air cooler review. Keep 'em comin'! Reply
rhx123 - Thursday, March 14, 2013 - linkI have a NH-L9i and I pretty much got it as a stock cooler replacement, my temps were fine on a i5-3470 but the noise was not.
I have a huge phobia of of a large chunk of metal damaging my machine when I move it, but for a multiplier-locked CPU getting a closed loop would be mad.
The NH-L9i is very quiet on idle, and more importantly the fan doesn't have an obvious tonality like some fans do. Reply
jrs77 - Thursday, March 14, 2013 - linkThe CM Hyper 212 Evo is still the best cooler, when you take it's price into account. Additionally you can make it even better with a $15-fan like the Akasa Apache PWM, which outperforms the stock-fan in both: noise and airflow. And even with an additional fan you're still paying less then for the other bigger coolers.
The AIO-liquid coolers are not really that impressive imho. I've had a Corsair H50 and H60 and an intel AIO-liquid cooler and allthough they showed better temps, the pumps and fans were loud and made irritating high-pitched noises. Not to mention that I had to RMA both Corsair-coolers (the H50 even twice) because the pump made rattling noises.
Also, for the money of them you can get a very good aircooler, performing just as well, especially if you're not overclocking. With regards to that, you should test a Prolimatech Genesis with two silent 140mm fans sometime. Reply
A5 - Thursday, March 14, 2013 - linkTo be fair, the H50 and H60 are the two cheapest CLCs on the market. If one is going that route, this testing shows the larger CLCs to be the ones to look at. The "cheap" ones don't really perform appreciably better than the CM 212 EVO and cost 50+% more. Reply
HisDivineOrder - Thursday, March 14, 2013 - linkPumps fail. That's enough for me right there to stay air. Sure, fans fail, too, but with a CLC you have the fans AND the pump at risk of failure. With air cooling, it's just the fan.
The difference between those coolers--air and water--is so small so as to be insignificant in day to day usage. The only reason someone should go for water cooling is if they want to break some speed records, but CLC should stay out of mainstream, every day systems.
Imo. Reply
Rick83 - Thursday, March 14, 2013 - linkIs there an error in the noise chart?
How can the PWM L9i be louder than the 100% L9i?
Especially, as in the text it doesn't say so.
Would be great if you could fix that. Reply
DanNeely - Thursday, March 14, 2013 - linkThanks for finally reviewing a Coolermaster 212 series unit; because their ubiquity gives lots of people a known reference point to compare performance with.
Could you add a YateLoon fan to your next fan roundup for the same purpose since they're one of the most popular budget 120mm fans? Reply
Beenthere - Thursday, March 14, 2013 - linkDustin - Again you display a strange and absurd POV on HSFs...
"...and if for whatever reason a closed loop cooler isn't on your list..."
Why would any technically astute consumer have a CLC on their "list" of desirable CPU coolers when CLCs are inferior in every typical CPU cooling metric used by consumers, including thermal efficiency, noise, cost and reliability. If you ignore all of the obvious reasons to not buy a CLC and just buy one because you want one or don't know any better, that is fine but no one with a technical clue would buy or recommend a CLC based on merit. Reply
extide - Thursday, March 14, 2013 - linkHow do you measure thermal efficiency? Just by how cool it gets the cpu? If so then CLC's do well.
Noise wise, has a lot to do with the fans and can be very similar to other coolers.
Cost? They are a bit expensive but their ability to cool well and also exhaust heat directly out the case is typically enough justification. I mean we are only talking about maybe $20 max, far less than a tank of gas even.
Reliability? I have had two in service for quite a while now and they have been fine but I can see how adding a pump into the mix is a recipe for lowering overall reliability potential.
However the simple fact is water moves heat better than heat-pipes, period. So you can move heat to a larger radiator, and also put that radiator in a larger variety of places. That is why even the small closed loop coolers do well. I have built several full custom loops in the past, and the closed loop coolers are not nearly as good as a high end custom setup, but FAR easier to get going and little to not maintenance. They have their place IMHO. They are not perfect but they definitely have their place.
Do you have any facts or reasons behind your statement or are you just saying stuff because it sounds cool? Maybe your idea of technically astute is incorrect, or you are simply not technically astute yourself. Reply
cjs150 - Thursday, March 14, 2013 - linkOf course there is the downside to water coolers. They are spot not area coolers. Air will cool everything (to a certain extent) in the case as it flows over it, water will only cool those spots which have a waterblock.
That is why you need to have decent airflow in a watercooled case - if not you fry the RAM (and yes I have done that) Reply
DanNeely - Thursday, March 14, 2013 - linkA few years ago I saw a CPU waterblock by a low-tier vendor that had brackets for a down blowing fan on top to keep the ram/mosfets from baking; and have always wondered why none of the other vendors have ever offered anything similar. Reply
mevans336 - Thursday, March 14, 2013 - linkI would love it if there were a way for the noise to be recorded so we can listen. Sure dBA numbers are great, but the actual pitch of the sound emitted is very important. I also have a hard time translating dBA numbers into perceived sound increase. I have a Noctua NH-D14 and according to your charts, there is only a 2dBA increase from silent to 100%. I would have guessed it to be MUCH larger than that as the perceptible sound increase from silent to 100% in my rig is massive. The pitch/tone of the sound (if that's the right terminology) at 100% changes drastically too. Reply
kmi187 - Thursday, March 14, 2013 - linkHere in Europe the DarkRock Pro is typically 1 to 2 euro's cheaper than the Noctua NH-D14, sometimes a bit cheaper even, if you can be bothered to look around. The new BeQuiet Shadow Rock also performs quite well imho, haven't used it myself but it's the cooler we put in budget systems at the shop whenever coolermaster EVO's aren't available. Reply
IanCutress - Thursday, March 14, 2013 - linkWe used the original Dark Rock Pro for an ASUS S2011 contest early last year, and it was quickly overwhelmed by the heat generated from the CPU past 5 GHz. So much that we had to force extra pressure on the socket so the processor didn't downclock and bork the scores. Reply
lwatcdr - Thursday, March 14, 2013 - linkGood review. The only thing I would suggest would be to also use a test bench for testing the coolers so you can take the case out of the equation. I would still test in a case as well but pick one you really like to build in because you will need to do it forever. Of course maybe you have.
Now you just need to test every cooler in every case and with every CPU. Can you have it by next week? Reply
wongwarren - Thursday, March 14, 2013 - linkNo sorry the Plus' fan is better than the Evo's fan. Reply
lichoblack - Thursday, March 14, 2013 - linkWhat about comparing low-profile coolers with some CLC's? Given the new trend towards smaller cases, and the height restriction of those microATX (Thermaltake LANBox for instance) or microITX cases (a LianLi one has 38mm height restriction, fitting for the noctua reviewed here) it would be interesting to compare a CLC to a compact cooler that has to be smaller than, say 100mm height. Reply
shaolin95 - Thursday, March 14, 2013 - linkGood stuff. I hope you add the Thermaltake Water 2.0 extreme to the mix.
I moved from D14 to it and love it. Reply
stennan - Thursday, March 14, 2013 - linkHey Dustin, great review!
Some friendly feedback: could you show some more pictures of the coolers tested earlier in review/roundup? It wasn't until the last page that the coolers were shown, also pictures of the cooler on the motherboard or in the case would be nice.
Keep up the work! Reply
cbrownx88 - Thursday, March 14, 2013 - linkI'd buy a Noctua cooler in a heartbeat if they didtn have those god awful colored fans. Reply
cmdrdredd - Thursday, March 14, 2013 - linkYou can use any 140mm fans you want Reply
mapesdhs - Friday, March 15, 2013 - link
Thoroughly agree! I bought a Noctua NF-A15 140mm to replace the stock rear fan in a
Coolermaster HAF 932 case. The Noctua fan performs fantastically well, but the colour
scheme is horrible. Having said that, Noctua's packaging and presentation is very good.
Opening the fan pack feels like a special event, it all has a certain luxury sheen which at
least makes one feel the high price is going to be worth it.
Ian. Reply
K1wi - Thursday, March 14, 2013 - linkI'd love the NH-L12 for a compact build as I'm a huge Noctua fan (best post-purchase support I've ever encountered), but it looks like it blocks the top PCI-e slot, so its a no-go for me. Its a pity because it looks like it only barely does... I wonder why they didn't choose to offset it to stay out of the PCI-e area and rather more over the top of the board where most ITX boards place their chipset stuff etc.
That only leaves the NH-L9i, which is more about reducing noise than improving thermals :( Reply
seven2nine - Thursday, March 14, 2013 - linkunder
Ease of installation
first paragraph "surrounding all the coolers here but but...." Reply
Lord 666 - Thursday, March 14, 2013 - linkAfter happily winning a z77 Sabertooth on Anandtech, was bummed my existing Zalman would not fit over the armor.
Without a doubt, will the NH-D14 fit? Reply
garadante - Thursday, March 14, 2013 - linkHonestly, these closed loop liquid cooler results aren't necessarily valid, as fifteen minutes of load testing probably isn't enough to thermally saturate the coolant. As soon as the coolant is thermally saturated, shouldn't the performance be based purely on the heat transfer of the radiators between the cooling medium, intake air, and the heat transfer medium, the coolant? At this point, I imagine a high end air cooler would perform more consistently in the long run.
Liquid cooling really shines with actual cooling loops, built yourself, with high end components, large radiator surface area, and more coolant to thermally saturate than is present in these closed loop coolers. There's only so much heat a 120mm closed loop cooler can dissipate, once the coolant reaches it's thermal saturation point.
These closed loop coolers are better for bursts of activity, but I have my doubts with them in extended torture testing. Anyway, I'd rather use a 480mm radiatior, or even a 480 paired with a 240/360, so I can run the fans at nothing/almost nothing overnight, with the heat capacity of the coolant taking care of the cooling, the only sound coming from the pump. Reply
ShieTar - Friday, March 15, 2013 - linkPotentially good point, but lets throw some numbers in to test it:
Heat Capacity of water is about 4 J/g/K, so if the closed-loop system come with 1/4l of water (I doubt it is more than that), they can take 1 kJ/K. The overclocked 2700K can possibly touch 100W when overclocked and stressed, so it puts out enough power to heat up the water by 1K every 10 seconds, or 90K over 15 minutes if you ignore the cooling effect of its radiator.
With this amount of power I would guess that this small, closed-loop systems are already relatively saturated and stable. Of course if you have a big system with 4 liters of water and a few Kg of radiator metal, you are looking at a much higher heat capacity of more than 20kJ/K, and if you just use normal loads (~50W) instead of a torture test, you could indeed cool for an hour or two on heat capacity alone. If you add an overclocked 680 or 7970 to the loop though, even this big system should hit saturation within much less than one hour. Reply
mapesdhs - Friday, March 15, 2013 - link
I talked to a German company which specialises in water cooling. They told me that to achieve
cooling performance "significantly better" than a high-end air cooler would require one to spend
at least 200 UKP ($300+). Otherwise, unless there are other considerations, a water cooler is
not going to beat a good air cooler.
This is why I keep bagging used TRUEs, etc. off eBay when I can, typically get them with
fans included for around 10 to 17 UKP. Also just bought a Venomous-X for only 25 UKP total.
Ian. Reply
garadante - Friday, March 15, 2013 - linkI actually imagine that in the 240/280mm closed loop coolers, there's easily more than .25 liters of coolant. Perhaps even approaching a liter or more, depending on the size/density of radiator piping and the tubing.
If your numbers are closer the accurate, than that's a fair enough way to say 15 minutes is likely enough, but still, I'd like to see 30-60 minute tests for the best performers, or even longer. Run those 280mm radiators for 1-2 hours and see how much/if at all that affects performance. Because on that slight change that it -does- affect it significantly, these numbers posted in the review are absolutely meaningless and misleading. Reply
coffeejunkee - Friday, March 15, 2013 - linkWell, interesting results to say the least. Tom's Hardware and X-bitlabs have reviews up as well comparing aio's to NH-D14 and Phanteks PH-TC14. Their results are quite different from this. For example in the X-bitsreview the H55 is easily beaten by PH-TC14 but here the H55 does better than the NH-D14. Something's not right, and it's probably called outtake fan. Reply
Nfarce - Friday, March 15, 2013 - linkJust remember that there are a lot of variables in different entities testing the same cooler, not the least of which is hardware including the case itself, and the success of how well the coolers are attached to the CPU with paste to minimize gaps. Then you have ambient temperature and altitude differences, etc. I wouldn't trust one review to be better or worse than another review of the same cooler. You are better off trying to find a pattern among all the coolers tested you are interested in and see which one mostly stays on top. Reply
coffeejunkee - Saturday, March 16, 2013 - linkWell, yes that's the reason I comment. I read many cooler reviews and I'm aware you can't compare them on an absolute basis, too many outside variables for that. But the results of this one have me scratching my head. This is simply the first time I see an aio like H55 do better than the NH-D14 and it just doesn't make much sense to me. I mean, look how thin the H55 radiator is and then look at the massive 1 kg of copper and aluminium which is the NH-D14. Ok, so H55 has higher rpm fan, but the dual fan setup on the NH-D14 counters that.
Also, Hyper 212 is a nice heatsink if you can get it around $30 but just 1.6 degree difference vs NH-D14? Which weighs like twice as much and has 2 fans, one even a 140mm model? Maybe using the NH-L12 bracket isn't so ideal afterall (also might be nice to mention regular NH-D14 doesn't come with pwm fans). Reply
mapesdhs - Friday, March 15, 2013 - link
I wish you'd included the Phanteks PH-TC14PE. It's cheaper than the NH-D14, looks nicer
and in many reviews performs better.
Ian. Reply
Nfarce - Friday, March 15, 2013 - linkI've been loving my NH-D14 on a 4.8GHz 2500k for two years solid now. Even in summer indoor ambient temps of 80F (27C), it never gets above 55C at that high level o/c running 1.38v. Of course the modded Antec Nine Hundred it sits in has excellent airflow too.
And two years ago I paid $85 for the thing, so the price has not come down at all, which speaks volumes about the continued demand for them. Best $$ I ever spent under $100 on a piece of hardware. Reply
Havor - Saturday, March 16, 2013 - linkI don't get all the bias of the reviewer against the NH-L9i, yeah for normal PC use its pretty much useless, but thats not ware its made for.
Its a HTPC/small form factor cooler, and it fits in to places ware its big brothers don't fit, its real competition is the Scythe Shuriken series and some other low profile solutions. Reply
Lycros - Saturday, March 16, 2013 - linkAnyway you can use the same fan(s) across all of the heatsinks next time? Reply
ellroy80 - Sunday, March 17, 2013 - linkDustin, your review of the NH-L9i is really not fair. It states on the Noctua website that "The NH-L9i is a highly-compact low-profile quiet cooler designed for use in small form factor cases and HTPC environments. While it provides first rate performance in its class, it is not suitable for overclocking and should be used with care on CPUs with more than 65W TDP." So your usage scenario is really not applicable to this cooler. Any chance you could re-test it with, say, an i3-3225? Reply
lichoblack - Monday, March 18, 2013 - linkI have to agree that the review paints the cooler in bad light, but instead of using another CPU, I'm more game with changing the restrictions: test small coolers and see how they fare. The NH-L9i/L9a have a very low height, and you can use them in very, very restrictive cases (thinking of an htpc/emu case using a Lian-Li PC-Q12, then you can only use a cooler up to 55mm, so you can use a stock intel fan, but not an AMD stock fan. see:http://www.lian-li.com/v2/en/product/product06.php... Not many coolers fit this bill, and big air just doesn't fit this. CLC could, depending on the case, but big air can't. So more small aftermarket coolers so we can better paint the small air picture :) Reply
andymcca - Monday, March 18, 2013 - linkGlad to see the CM 212 EVO in the line up. I was guessing when I opened the article that it would be omitted in favor of more expensive models. Thanks for including it, as I think people overlook it purely based on price!
I've been happily using a fanless 212 Plus for years in my low noise desktop and have been very pleased! Reply
boe - Monday, March 25, 2013 - linkNice report. I was bumming the Scythe ones were not included as that is what I use 90% of the time. Reply
bobbyto34 - Wednesday, March 27, 2013 - linkFor my Fractal Node 304 and intel DH77DF mini itx board, I was hoping that the Noctua L9i would be ok... it was not the case on the compatibility list of noctua.
I finally found the thermalright AXP 100 that fitted the board. The only drawbacks :
- you cannot install the backplate because of chips on the bottom of the motherboard. You only put the screws.
- covers some ports (CPU PSU, hd audio, system fan). You have to install these cables before installing the cooler
- really close to the pci express port Reply


text:
The Bulldozer Aftermath: Delving Even Deeperby Johan De Gelas on 5/30/2012 1:15 AM EST
84 Comments
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thunderising - Wednesday, May 30, 2012 - linkGlad AMD has "Greater Performance" planned sometime in the future. Wow! Reply
themossie - Wednesday, May 30, 2012 - link"There are also other factors at play, though, as it's already known that StarCraft II doesn't use more than two cores; theinstead, it's likely the..."
(feel free to remove comment after fixing this) Reply
Nightraptor - Wednesday, May 30, 2012 - linkI am wondering if it would be possible to compare the processor performance of the Trinity A10 with a underclocked FX-4100 set to the same frequencies (I don't know if it is possible to disable the L3 cache on the FX-4100). This might give us a rough idea of how much the improvements of Piledriver have bought us. Just doing rough math in my head it would seem that they have to be pretty significant given how a FX-4100 compared to the Phenom II X4's (it lost alot, if not most of the time t of the time). The new A10 Trinity's on the other hand seem to win most of the time compared to the old architecture. Given that the A10 is a Piledriver based FX-4XXX series equivalent minus the L3 cache it would seem that Piledriver brought very significant enhancements. Either that or the Phenom II era processors responded much more poorly to the lack of L3 than Piledriver does. Reply
coder543 - Wednesday, May 30, 2012 - linkI was hoping they would be doing the same thing, even though it would be challenging to draw real information out of comparing a desktop processor and a mobile processor. Reply
SleepyFE - Wednesday, May 30, 2012 - link+1 Reply
kyuu - Wednesday, May 30, 2012 - link+2
If you can figure out some way to do a comparison and analysis of Piledriver's performance vs. Bulldozer, I think a great many of us are interested to see that. From benchmarks, it seems like Piledriver improved a great deal over Bulldozer, but it's difficult to tell without being able to compare two similar processors. Reply
Aone - Wednesday, May 30, 2012 - linkYou can compare A10-4600M or A8-4500M versus mobile Llano or Phenom or even Turion to see tweaked BD is nothing of spectacular. For instance, in most cases A8-4500M (2.3GHz base) loses to Llano A8-3500M (1.5GHz base). Reply
Nightraptor - Wednesday, May 30, 2012 - linkWhere are you getting the benchmarks from that a Trinity loses to Llano. In almost all the benchmarks I have been able to find (with the exception of a few) it seems that Trinity beats Llano, hence the original post. If the Piledriver enhancements were very minor I would've expected Trinity (a hacked quad core) to lose to Llano most of the time (a true quad core). This didn't appear to happen - at least not in the anandtech review. Reply
Aone - Wednesday, May 30, 2012 - link"http://www.notebookcheck.net/AMD-A-Series-A8-4500M...
Look at "Show comparison chart". Great info! Reply
Nightraptor - Thursday, May 31, 2012 - linkI'm not a big fan of the reliability of that website - They tend to be pretty scant on the test circumstances and configurations. Furthermore I'm curious where they are getting the informaiton for the A8-4500 as to the best of my knowledge the only Trinity in the wild at the moment is the A10 which AMD sent out in a custom made review laptop. All they list is a "K75D Sample". Reply
Schmide - Wednesday, May 30, 2012 - linkI do remember from some analysis that the L2 cache reads were as slow as main memory. That's great if you hit a L2 cache, but it's not going to buy you anything if it's that slow. Reply
SocketF - Wednesday, May 30, 2012 - linkImpossible, you probably mix some things up, maybe latency and bandwidth? Reply
Schmide - Wednesday, May 30, 2012 - linkYup. It was late at night, I was thinking writes. the L1 write through basically makes L1 writes the same as L2 writes. Reply
Homeles - Wednesday, May 30, 2012 - linkNot even close. L2 is about 10 times faster than main memory.
http://www.anandtech.com/show/4955/the-bulldozer-r... Reply
jcollake - Wednesday, May 30, 2012 - linkThrough research here at Bitsum on the AMD Bulldozer platform (specifically the 9150), I found a couple things of interest.
First, disabling CPU core parking seems to make a big difference in performance. I believe that by default the CPU core parking is just too aggressive. I wrote a tool to let you enable or disable CPU parking in *real time* without a reboot, so you can test this yourself. It is called ParkControl, http://bitsum.com/about_cpu_core_parking.php . For *me*, it seemed to make a night and day difference.
Second, I am working on a neat little benchmarking tool called ThreadRacer, currently only in alpha prototype. It allows you to really see the effects of these paired cores, and how much it matters that the scheduler is properly aware of them. Take this 1 second or so sample, as seen in the screenshot here (downloads available, but it is an early prototype that I'll quickly be finishing up): http://bitsum.com/forum/index.php/topic,1434.0.htm...
The scheduler update that Microsoft issued of course treats these paired cores as it would a hyper-threaded core. Indeed, the concept is very similar, except perhaps to avoid patents, AMD took the 'share a little' instead of 'share a lot' approach when it comes to shared computational resources. This was the proper way to *quickly* address the issue, but I believe the scheduler is still suboptimal on these processors (likely to be resolved in Windows 8 or a later update to Windows 7/Vista).
For Bulldozer, as you know, they are two real processors, but because they have shared dependencies, the performance can really be drained if the other processor in the 'pair' is busy. You can see the effects from ThreadRacer, the core without its pair busy quickly out-paced the paired cores that were both busy. Reply
jcollake - Wednesday, May 30, 2012 - linkI should have also mentioned that ThreadRacer also allows you to see how a single CPU consuming thread gets swapped around to different cores (the multi-core thread in the utility). This is its other use. The less the thread gets swapped from core to core, the greater the performance will be. It is interesting to compare and contrast the behavior of the scheduler. I fully believe that most the problems with Bulldozer are due to the Windows scheduler, something that could be tested by using linux and replacing the scheduler with a custom one, or an off the shelf alternative that may behave substantially differently than the Windows scheduler. Reply
SocketF - Wednesday, May 30, 2012 - linkSome people running BOINC programs have reported that Windows-applications run faster when they use a Linux and WINE or a VM.
The Win-scheduler especially hurts AMD chips, because of the huge exclusive caches. If a thread on an intel CPU is switched to another core, it can load the warmed up L2 portion from the L2 inclusive L3.
I did some google-search and it seems that under Linux, each core has its own run-queue, whereas on Windows, there is only one run queue for all cores.
But i didn't delve into it deeply, there are so many different schedulers for Linux, seems to be a complex issue ;-)
Btw. your link to download is off limits for non-members of your discussion board:
The topic or board you are looking for appears to be either missing or off limits to you.
Please login below or register an account with Bitsum Forums.
Maybe you can upload it somewhere else? Reply
jcollake - Saturday, September 01, 2012 - linkSorry for the late reply. First, the forum permissions were fixed. Second, the utility (still in early stages) is included in Process Lasso *and* available here: http://bitsum.com/threadracer.php Reply
eoerl - Wednesday, May 30, 2012 - linkVery interesting article, together with the hardware.fr report there's a lot of information. One question though, if you read commentaries : you didn't speak much about the influence of compilers. This proved to change a lot of things on Linux (see phoronix extensive tests on both ivy bridge and bulldozer depending on compiler used and compiler options, for example
Benchmark results really change a lot with bulldozer, much more than with ivy or sandy bridge. Do you think AMD lost being oversensitive to compiler optimisations, due to a very original architecture ? Reply
JohanAnandtech - Thursday, May 31, 2012 - linkI deliberately avoided the compiler issues as this would make the article too convoluted. But notice that what we found is not influenced by compiler choice: we find the same indications in SAP and SQL server (compiled by "conservative" compilers and compiler settings) as in CPU CPU 2006, which uses the best optimized settings and compiler as possible. Reply
ArteTetra - Wednesday, May 30, 2012 - link"A core this complex in my opinion has not been optimized to its fullest potential. Expect better performance when AMD introduces later steppings of this core with regard to power consumption and higher clock frequencies."
You don't say? Reply
JohanAnandtech - Thursday, May 31, 2012 - linkA quote by a reader, not ours :-). The idea is probably that Bulldozer was AMD's very first implementation of their new architecture. Reply
haplo602 - Wednesday, May 30, 2012 - linknow this was a great read. finaly something interesting (the consumer benchmarks are NOT intereseted anymore for me).
I hope there will be a differential analysis once you have Piledriver CPUs available. Reply
JohanAnandtech - Thursday, May 31, 2012 - linkPiledriver analysis: definitely. Thanks for the encouraging words :-) Reply
mikato - Friday, June 01, 2012 - linkI agree - great critical thinking in this article! This subject definitely needed more research. Reply
Spunjji - Wednesday, June 06, 2012 - link+1. This is the sort of thing I come here for! Reply
Beenthere - Wednesday, May 30, 2012 - linkExpecting Vishera to be an Intel killer is foolish as it's not going to happen and there is no need for it to happen. Ivy Bridge is very much like FX in that it's only 5% faster than SB and runs hot. At least FX chips OC and scale well unlike Ivy Bridge.
If AMD can use some of the techniques imployed in Trinity they should be able to get a 15+% improvement over the FX CPUs. This combined with higher clockspeeds now that GloFo has sorted 32nm production should provide a nice performance bump in Vishera.
95% of consumers do not buy the fastest, most over-hyped and over-priced CPU on the planet for their PC or server apps. Mainstream use is what AMD is shooting for at the moment and doing pretty well at it. Eventually they will release APUs for all PC market segments that perform well, use less power and cost less than discrete CPU/GPU combo. THAT is what 95% of the X86 world will be using. Reply
Homeles - Wednesday, May 30, 2012 - link"Ivy Bridge is very much like FX in that it's only 5% faster than SB and runs hot"
I think you need to go read about Intel's tick-tock strategy.
Also, unlike Bulldozer, Ivy Bridge was a step forward. A small one, but performance per watt went up, while with Bulldozer it often went backwards.
Process maturity from GloFo will help, but probably not as much as you would think.
Finally, "95% of users" aren't going to benefit best from a processor built with server workloads in mind. Even with server workloads, Bulldozer fails to deliver. APUs are definitely the future, but keep in mind that Intel's had an APU out for as long as AMD has. If you think that AMD's somehow going to pull a fast one on Intel, you're delusional. Intel and Nvidia as well are very, very well aware of heterogeneous computing. Reply
The_Countess - Wednesday, May 30, 2012 - linklooking at how much the performance per watt went up with piledriver compared with llano, I think they''ll have a lot more headroom on the desktop and server space to increase the clock frequencies to where they are suppose to be with the bulldozer launch. Reply
Homeles - Wednesday, May 30, 2012 - linkYeah, Piledriver will likely perform the way AMD had intended Bulldozer to perform. Reply
Spunjji - Wednesday, June 06, 2012 - linkAgreed. That will be nice! Reply
haukionkannel - Wednesday, May 30, 2012 - linkVery nice article! Can we get more thorough explanation about µop cache? It seems to be important part of Sandy bridge and you predict that it would help bulldoser...
How complex it is to do and how heavily it has been lisensed? Reply
JohanAnandtech - Thursday, May 31, 2012 - linkDon't think there is a license involved. AMD has their own "macro ops" so they can do a macro ops cache. Unfortunately I can not answer your question of the top of head on how easy it is to do, I would have to some research first. Reply
name99 - Thursday, May 31, 2012 - linkOh for fsck's sake.
The stupid spam filter won't let me post a URL.
Do a google search for
sandy bridge Real World Technologies
and look at the main article that comes up. Reply
SocketF - Friday, June 01, 2012 - linkIt is already planned, AMD has a patent for sth like that, google for "Redirect Recovery Cache". Dresdenboy found it already back in 2009:
The BIG Question is:
Why did AMD not implement it yet?
My guess is that they were already very busy with the whole CMT approach. Maybe Streamroller will bring it, there are some credible rumors in that direction. Reply
yuri69 - Wednesday, May 30, 2012 - linkHowdy,
FOA thanks for the effort to investigate the shortcomings of this march :)
Quoting M. Butler (BD's chief architect): 'The pipeline within our latest "Bulldozer" microarchitecture is approximately 25 percent deeper than that of the previous generation architectures. ' This gives us 12 stages on K8/K10 => 12 * 1.25 = 15.
Btw all the major and significant architectural improvements & features for the upcoming BD successor line were set in stone long time ago. Remember, it takes 4-5 years for a general purpose CPU from the initial draft to mass availability. The stage when you can move and bend stuff seems to be around half of this period. Reply
BenchPress - Wednesday, May 30, 2012 - link"This means that Bulldozer should be better at extracting ILP (Instruction Level Parallelism) out of code that has low IPC (Instructions Per Clock)."
This should be reversed. ILP is inherent to the code, and it's the hardware's job to extract it and achieve a high IPC. Reply
Arnulf - Wednesday, May 30, 2012 - linkUgh, so much crap in a single article ... this should never have been posted on AT.
You weren't promised anything. You came across a website put up by some "fanboy" dumbass and you're actually using it as a reference. Why not quote some actual references (such as transcripts of the conference where T. Seifert clearly stated that gains are expected to be in line with core number increase, i.e. ~33%) instead of rehashing this Fruehe nonsense ? Reply
erikvanvelzen - Wednesday, May 30, 2012 - linkYes AMD totally set out to make a completely new architecture with a massive increase in transistors per core but 0 gains in IPC.
Don't fool yourself. Reply
Homeles - Wednesday, May 30, 2012 - linkIt's a more intelligent analysis than your sorry ass could ever produce. Getting hung up on one quote... really? Reply
Taft12 - Wednesday, May 30, 2012 - linkJohan, this is the best article I've read on Anandtech in quite some time, even better than Jarred, Ryan and Anand have come up with lately.
The level of analysis goes far, far beyond just what the benchmarks show.
Bravo! Reply
JohanAnandtech - Thursday, May 31, 2012 - linkGreat! Good to read there are still people that like these kinds of analysis!
:-) Reply
ct760ster - Wednesday, May 30, 2012 - linkWould be interesting if they could test the aforementioned benchmark in an OS with a customizable kernel like GNU-Linux since code optimization is not possible in most of the proprietary format benchmark. Reply
alpha754293 - Wednesday, May 30, 2012 - linkWhat about the lacklustre FPU performance?
The very fact that the FP has to be shared between two integer cores and as far as I know, it cannot run two FP threads at the same time, so for a lot of HPC/computationally heavy workloads - Bulldozer takes a HUGE performance hit. (almost regardless of anything/everything else; although yes, it counts, but remembering that CPUs are glorified calculators, when you take out one of the lanes of the highway and two-lane traffic is now squeezed down to one lane, it's bound to get slower.) Reply
The_Countess - Wednesday, May 30, 2012 - linkexcept the FP CAN run 2 threads at the same time.
only for the as yet pretty much unused 256bit instructions does it need the whole FP unit per clock.
in fact the FP can run 2 threads of 128bit, or 4 even of 64bit.
and a single CPU can use 2x128bit or both can use 1x128.
intel and AMD previously had only 1x128bit capability per core.
so there is no regression in FP performance per core. its just much more flexible. Reply
Zoomer - Wednesday, May 30, 2012 - linkFPU throughput is much more irrelevant nowadays, as many FP intensive HPC computations have already been ported to GPUs. Yes, there may be instances where there might be FP heavy and branchy, not easily parallelization or otherwise unsuitable, but such beasts are few and far between. I can't think of any, to be honest. Reply
Iger - Wednesday, May 30, 2012 - linkThanks a lot, that was a very interesting read! Reply
Rael - Wednesday, May 30, 2012 - linkAMD should fire all its marketing department, because these guys accustomed to lie at every announcement they make. The performance gains are multiplied by five or ten, and the per-core advancement, which is close to zero, is presented as 'significant'.
I don't believe these announcements anymore. Reply
jabber - Wednesday, May 30, 2012 - linkWhat the whole of the AMD Marketing team?
Thats Tim the caretaker and Trisha on the front desk isnt it?
I thought AMD's marketing budget was around $42. Reply
kyuu - Wednesday, May 30, 2012 - linkOh hai. You must be new to the human race. Marketing and "stretching the truth" have been synonymous since... forever. AMD is hardly exceptional in this regard. Stop believing anything any marketing department sells you, period. Reply
Homeles - Wednesday, May 30, 2012 - linkThis. Read 3rd party reviews (like AnandTech!) -- several of them -- and draw your conclusions from there. That's pretty much the point of reviews; if marketing teams could provide honest, reliable benchmarks over a wide range of applications, we'd have little need for 3rd party reviews. Reply
Mugur - Thursday, May 31, 2012 - linkWell... they actually did! Reply
moravista - Wednesday, May 30, 2012 - linkGreat article Johan! I have been reading your articles since the Pentium III / K6-2 days and have really enjoyed them! Thanks for sharing your insight! Keep 'em coming! Reply
JohanAnandtech - Friday, June 01, 2012 - linkGreat to hear from you. Did you used to participate at the different forums on a different callsign? Reply
muy - Wednesday, May 30, 2012 - linki want a phenom II x4 980+ on 32 nm. this whole idea of "lets put as many crippled dual cores on a die and smack a level 3 cache on top and call it out next cpu" is utter crap stuff that doesn't multi thread well (95 % of all stuff).
6 core bulldozer i bought to replace my amd x3 450 is slower than the chip i wanted to replace at the same clock speed. now i have a shiny asus rog mb, a x3 450 powering it, and a 6 core bulldozer gathering dust. what a waste of money that was.
shame i can't find any x4 970+'s anymore and amd is to foolhardy to keep manufacturing their best gaming cpu's, let alone do a shrink on them to 32 nm.
i can only imagine how much better a phenom 2 x4 9xx, default clocked at 4.2 ghz+ would be than any bulldozer. (and how much cheaper to manufacture considering the die size compared to the die size of bulldozer).
i just don't understand amd. Reply
Roland00Address - Wednesday, May 30, 2012 - linkMicrocenter has these following processors
1045t six core for $99
965 quad core black edition for $99
960t quad core black edition for $89 (this model is a disabled six core and has a possibility of unlocking to a 6 core. The 960t is a clearance processor so it is while supplies last. Reply
fic2 - Thursday, May 31, 2012 - linkThose are all 45 nm. He is wanting a tick - a die shrunk Phenom II.
Would have to agree with him. If AMD would do a die shrink they would have a killer product - assuming GloFo didn't f*ck it up. Reply
muy - Wednesday, May 30, 2012 - linkbulldozer doesn't do single threaded, highly branching (cough games cough) stuff well.
and before you say "some games use multiple cores", i'll say that 1 core running on 100 % and 7 cores at 5 % is not a good use of multi threading.
(1 * 100) + (7 * 5) = (1 * 100) + (1 * 35) - 1.35 cores used. this means that a DUAL core going at 10 % higher speed than the exampled 8 core would be 10 % faster than the 8 core 'using' it's 8 cores.
clock speed + ipc are the only things that matter 90% + of the time for games. Reply
wolfman3k5 - Wednesday, May 30, 2012 - linkPeople don't buy CPUs based on theoretical performance, ideology or brand loyalty (OK, some fan-boys do). Most of us are not computer engineers, and even if we where, it wouldn't matter, because at the end of the day only the end result would matter: performance, efficiency and price. Just like I didn't buy Intel because it looked good on paper back in the glory days of AMD (cca. 2005). So no matter how deep and involved these articles are, AMD still trails Intel when it comes to performance, and it will do so until their lazy and incompetent CPU engineers will get off their lazy buts and start working. The sole reason why Bulldozer was such a massive fail was because most of the design process was highly automated. So, stop slacking and start working lazy AMD engineers! Reply
Homeles - Wednesday, May 30, 2012 - linkBeing a "lazy" electrical engineer is practically impossible. The amount of work that has to go into making these processors simply function is quite massive. These guys work hard to get to where they are with their careers and work even harder to keep those careers. The margin of error here is also quite huge... a small flaw can create enormous performance penalties.
I'd be willing to bet that many, if not most of Bulldozer's shortcomings could be blamed on management. Saying it was "lazy engineers" is callous and ignorant. Reply
Zoomer - Thursday, May 31, 2012 - linkTrue. It's probably better out way back then, but synthesized, than to come out maybe next year with all their lovingly fully customized, hand placed transistors. That's if they don't go bankrupt first.
wolfman3k5's probably going to call nVidia, 3dfx, ATi (then), most FPGA program design houses, etc, lazy, too. Reply
misiu_mp - Monday, June 11, 2012 - linkA large margin of error means that you have a lot of space to make errors with little consequence.
You meant of course that engineers have small margins of error in their work. Reply
500MM - Wednesday, May 30, 2012 - linkhttp://images.anandtech.com/graphs/graph5057/42770...
If lower was better, AMD would have one kickass CPU. The caption is wrong. Reply
JohanAnandtech - Friday, June 01, 2012 - linkFixed, thx! Reply
weebnuts - Wednesday, May 30, 2012 - linkThe problem with all these benchmarks is that most organizations are going to be using this is Xen or Vmware uses. The idea is that with more cores, you can run more VM's especially if you are trying to implement Virtual Desktops. How do the processors compare when you are loading the server to 80-90% capacity with lots of VM's? That's a real world comparison I want to see. Reply
Iketh - Wednesday, May 30, 2012 - linkI was dying for information like this. Thank you!
And as for that quote on the first page by Iketh, that guy is a genious!! :D Reply
Aone - Thursday, May 31, 2012 - link1) Maybe i missed something but, Should "Higher is better" be for "Data Cache hitrate", i.e. opposite to cache misses?
2) And on the chart "L2 Cache hitrate", is it correct that "Opteron 6276" tag is shown on first line while "Opteron 6174" on the last line? I thought Opteron 6174 was faster in MS SQL than Opteron 6276. Reply
mrdcook - Thursday, May 31, 2012 - linkThere are a few new instructions in Bulldozer's architecture that, for certain specific computations, can make it 10X faster than Intel. For example, FMA. An FMA does a multiply and then an add as one instruction, rounding only once. Combining the multiply and the add isn't such a big deal (and in many cases can even be counter-productive), but rounding only once is very important in some cases.
For example, assume you have 3 digits of accuracy and want to calculate (1.23 * 2.31 - 2.84). Without FMA, you calculate Round(1.23 * 2.31) = 2.84, then you calculate Round(2.84 - 2.84) = 0. With FMA, you calculate 1.23 * 2.31 = 2.8413, then you calculate Round(2.8413 - 2.84) = 0.0013. While that may seem contrived (it was!), the difference is significant in certain simulations and calculations.
When doing math, computers have a very specific level of accuracy -- a certain number of digits of precision. If you want your simulations to come out right, you have to take these limits into account. Learning how to account for the computer's rounding errors is a bit of a black art.
Mathematicians design algorithms in terms of matrix multiplications and dot products, and if you translate those algorithms directly into computer multiplications and additions, you tend to end up with a lot of cancellation errors like the example given above. You can hire a computer science grad student to rework your algorithm to not lose accuracy, but that is expensive and has to be done for every new algorithm. Or you can use an FMA for the dot products and the matrix multiplications (the high-accuracy dot product and matrix multiplication libraries already do this).
FMA in software is slow. Single-precision emulated FMA isn't too bad since you can use double-precision to help with the hardest bits of the emulation. The result is that you can do one fmaf in about 4X the amount of time it would take to do a single a*b+c. However, SSE2 allows you to do 4 a*b+c at a time, so emulated single-precision FMA ends up being about 15X slower than optimized SSE2 non-fused multiply-add. Double-precision is harder, taking about 10 times longer than a single a*b+c, so it ends up being 20X slower than non-fused multiply-add.
Admittedly, the target market for FMA is probably smaller than a breadbox, but those who need it really need it. And as it becomes more common, it'll only become more important. For now, since only Bulldozer has it, nobody is going to care. Reply
BaronMatrix - Thursday, May 31, 2012 - linkThere are admittedly only two viable X86 licensees in America and one of them sucks... Reply
shodanshok - Thursday, May 31, 2012 - linkHi Johan,
first of all, let me thank you for your wonderful analysis on Bulldozer architecture. I read it with great interest.
However, I think that you left out a very important thing to mention: L1/L2 cache read/write bandwidth. Especially for L2, while latency is an important thing, throughput can be an even more crucial one.
The key point is that Bulldozer has an write-through L1 cache, so all L1 writes are more or less immediately broadcasted to L2 cache. Some small writes can be effectively cached inside a write-back combining buffer called Write Combining Cache (WCC), but this cache is only 4KB in size per the entire module. So, streaming writes will immediatly fill the WCC and bring down L1 cache speed to L2 levels.
This can really hamper CPU performance. Obviously, AMD went this road for some understandable reasons, however, the WCC is really too small to cache much data and the L2 is way too slow to efficiently serve L1 write requests.
This bring us to another point: L2 cache is slow. Comparing this with the super-fast (but much smaller) L2 Intel cache, it has no hope; it is more or less at Intel's L3 level.
Here you can find my analysis of AMD Bulldozer architecture: http://www.ilsistemista.net/index.php/hardware-ana...">AMD Bulldozer analysis
Note that, while I collected and normalized data from multiple web site, I left very clear what was the original reference (so that you can easily verify my data).
Thanks. Reply
shodanshok - Thursday, May 31, 2012 - linkMmm... the link was malformed in the previous message.
The correct one is: http://www.ilsistemista.net/index.php/hardware-ana...
Thanks. Reply
name99 - Thursday, May 31, 2012 - link"First of all, in most applications, an OOO processor can easily hide the 4-cycle latency of an L1 cache."
I know you guys are interested in the question --- why does Bulldozer frequently suck? --- rather than the question ---why is Sandy Bridge so much better? --- but it is this latter question that interests me the most.
What strikes me, on going through all this data (including information that is NOT in the article, and on my experience back in the day when I was writing assembly and counting cycles) is that the "eventual cost" of misses that go all the way to RAM is not covered in the article, and I suspect this is a large part of the issue.
What I mean here is the following: consider an extremely simple model --- an L1 hit takes 1 cycle, an L1 miss that goes to RAM takes 100 cycles. Then a 97% L1 hit rate takes a total of basically 400 cycles; a 99% L1 hit rate takes 200 cycles --- apparently minor differences have a huge effect! But that's not the point I want to focus on.
Let's make the model more complicated. First let's make L1 hit cost more realistic --- 4 cycles. As the article says, this is, for the most part, trivially hidden by the OoO engine. But then why can't the OoO engine also hide all or most of the cost of all those cycles to RAM?
And that, I think, is where the Intel advantage is. They do such a good job with their OoO engine.
At a gross level, OoO engines all look kinda the same --- look at a PPC 750 and an IB and, at a superficial level, they look similar. But firstly the IB has just so much larger buffers (what, 168 or so, compared to the 750s what, 6 or so) that, of course, it has a vastly larger stock of instructions it can keep chewing through as it waits for the RAM.
But, you say, AMD also has large buffers now. Yes, but it's not only the raw buffers. Whenever you start looking at these chips, you discover all sorts of weird limitations on what they can actually do to use all those buffers. I've no idea what the current exact limitations are, but the sort of thing you would have in the past is that maybe all the buffers are flushed on an interrupt or system call; or there'd be strange conditions that could occur where, although in theory the integer engine could keep going past a blocking FP instruction, it turned out to be easier to prevent some race condition by freezing the integer engine under these conditions.
Secondly while you're executing other instructions, waiting on your RAM, you may well execute a few more load/store instructions that again miss in RAM. How well do you handle these? Can you just keep firing out these load/stores, or do you block at the second (or third, or fourth)? Frequently these load-stores refer to the same cache-line that's already in play from the first L1 miss, and how do you handle that? the truly dumb thing, of course, is to send out ANOTHER memory request. Smarter is to suppress that, but you're still using load-store entries in the main "miss to RAM" data structures. Smarter still is to be aware that this line will be coming eventually, and use auxiliary data structures to hold info about this load/store.
It's these sorts of technical details, which don't appear in the gross specs (and sometimes not even in the detailed CPU descriptions) that make so much difference. They are obviously astonishingly difficult to get right. Intel has the manpower to worry about every one of them, AMD does not.
Point is --- if I had to look for a single difference between the the two, that's what I'd be looking at --- how much time is REALLY wasted waiting on DRAM in SB vs on Bulldozer. Reply
misiu_mp - Monday, June 11, 2012 - linkIt is the compiler's and Out-Of-Order engine's job to order loads, stores and other instructions to minimize the total execution time.
So making sure no stupid and unnecessary loads are being committed is what the OOO mechanism normally does.
There is no reason to suspect it is fundamentally broken in Bulldozer. Reply
IceDread - Friday, June 01, 2012 - linkIt really is simple, Amd did a Huge mistake.
The product is a bust, simple as that.
The next generation or the generations after that might be a whole different matter, but guess what? No one cares. It wont help the poor souls that bought this busted product.
It's annoying that Amd could not do better because now Intel reigns supreme and competes with itself . Reply
mikato - Friday, June 01, 2012 - linkI know I shouldn't feed the trolls but...
You say next generations might be a whole different matter - well what do you think is the point of learning about the Bulldozer architecture? The next generations are based on it. Reply
IceDread - Monday, June 04, 2012 - linkWhat is the point of releasing a product that does not outperform it's predecessor?
Hope that people will purchase the product anyway and learn it?
Which companies would be interested in this, how many? Why would they invest money into this? Reply
_vor_ - Saturday, June 02, 2012 - linkYes. I too would be interested in exactly what aspects you think Bulldozer failed and your design ideas and approach on how you would fix them. Do tell. Reply
wiyosaya - Friday, June 01, 2012 - linkPersonally, I think it is always nice to see in-depth articles like this that explain the details of the structure of a processor.
To me, it sounds like AMD has a foundation that with a few well-directed tweaks, may put them in contention with Intel again in the CPU arena. Though AMD has said that they are through competing with Intel, I truly hope this is not the case. Perhaps this is a marketing tactic remove focus from themselves after the enthusiast arena panned BD and its siblings.
I've built my systems with AMD for a long time; however, this time I went with Intel because I thought they had the better value. Perhaps the future will bring me back to AMD, however, I cannot see doing so right now simply because Intel has become the "value" line over AMD.
With an i7-3820 in my most recent rig, I think I picked the SB-E value processor. I run more than games, and some of what I run takes advantage of quad-channel memory.
In any event, I'm set for a while. Perhaps AMD will once again produce a superior product by the time I am ready for my next build. Reply
jamyryals - Friday, June 01, 2012 - linkWhat a great read, thanks! Reply
SocketF - Friday, June 01, 2012 - linkHi Johan,
thanks for the test, it is great.
However, on page 9 you have some trouble with percentage calculations. You wrote:
We get a 65% speed up (2x 0.71 vs 0.86), which is somewhat lower than the 80% predicted by the AMD slides discussing CMT.
This numbers are totally correct and within AMD's predictions. AMD promised 80% performance for the CMT-Bulldozer module, compared to an hypothetical Bulldozer CMP core, i.e. 2 (single) cores.
So you have to double your single-thread results, to get the score of 2 (single) Bulldozer cores (2 CMP cores). That gives: 0.86 x 2 = 1.72
Now compare that to the real performance of 2 CMT cores of one module, which is 0.71 x 2 = 1.42
1.42 are 82.6% of 1.72, which is better than AMD's 80% claim. Thus their claim holds. Everything's fine, don't worry.
Source of AMD's claim is e.g. here:
(sorry, didn't find it on anandtech)
Please update your article accordingly.
Oh and one last question, why did you add up the SMT scores but not the CMT scores? Seems odd, an IPC of "two threads", This is just weired. Furthermore it is somehow useless, because you cannot compare it directly with the CMT scores. A diagram should visualize the results not force the reader to do some re-calculations.
Thanks again
Erik Reply
Aone - Monday, June 04, 2012 - linkBulldozer's conception was wrong from the scratch.
I told it a few time, let's me explain it here again.
I'm sure everyone of you do remember AMD's own words "one BD module has 80% of throughput of two independent cores".
What does this mean in figures?
Let's take the performance of one core as 1.0 point. Therefore two BD modules would have 3.2 points or in other words less than 10% than 3.0 (performance of three independent cores).
Should I remind that with development of independent cores AMD wouldn't had wasted resources (engineering, transistors, money and time) on design and debugging the shared logic. The chip could have been much smaller due to the fact that the chip would have had only 1MB L2 and 2MB L3 per each core and no shared logic. And all of those released resources could have been allocated for development of a more advanced core.
You see that packing two cores inside a one module was wrong even on the conceptional level. I'm very curious who was the main supporter and decision maker of this approach in AMD.
AMD must through away BD conception and return to standard practice. The only question remains: Does AMD have long enough TTL to do it?
BTW, I recommend to look through Spec results again. The comparison of 12c Opteron 62xx w/ 12c Opteron 61xx is of special interest. And let's not forget that Opteron 62xx submissions have higher freq, faster memory and as well as more advanced compiler version and extended instruction set. Reply
TC2 - Monday, June 18, 2012 - linkI'm agree in 100%!!!
The BD uA is "unsuccessful" port from graphics uA. There is many and major drawbacks! Note for example one - to write an optimal software you must adopt an application at algorithmic level (in sense of thread specialization)! This is because the both BD-cores are not the same! Also they shares L1 IC, the number of elements is high, ... and many others uA weaknesses. Reply
evolucion8 - Tuesday, June 17, 2014 - linkNorthwood was 20 stage pipelines and Prescott was 31, not 39... Reply
tipoo - Wednesday, October 08, 2014 - linkWhere is the aftermath?
"But what about the fourth show stopper? That is probably one of the most interesting ones because it seems to show up (in a lesser degree) in Sandy Bridge too. However, we're not quite ready with our final investigations into this area, so you'll have to wait a bit longer. To be continued...." Reply

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