Always look at the date when you read a hardware article. Some of the content in this article is most likely out of date, as it was written on July 30, 2014. For newer information, see our more recent articles.
Hard drives (especially SSDs) are becoming faster and faster but have recently hit a performance wall due to the limitations of the current SATA specification. SATA III is rated for 6Gb/s, but in real-world scenarios is actually limited to a theoretical maximum throughput of only about 550-600MB/s. This is very fast but even current storage technology can theoretically go much faster than this.
M.2 is a new form of connectivity for SSD drives that allows drives to connect directly to the PCI-E bus rather than going through a SATA controller. By bypassing the SATA controller a M.2 drive can have a theoretical maximum throughput as high as 2GB/s. To put this into perspective, that is over three times faster than the 600MB/s SATA is limited to!
One thing to be aware of is that not all M.2 drives are created equally. M.2 includes backward compatibility with SATA, so there are some M.2 drives on the market that still use SATA instead of PCI-E and are thus still limited to 550-600MB/s. Even on the PCI-E drives, depending on the version they can use either 2 or 4 PCI-E lanes (x2 or x4) which can dramatically impact performance. One neat thing with these PCI-E M.2 drives is that you don't actually need a motherboard that has an integrated M.2 slot. In fact, you can use a very simple adapter to plug a M.2 card into almost any PCI-E slot on your motherboard. This makes it very easy to add a high-speed M.2 drive to almost any system.
First, since most motherboards with M.2 slots currently only run at PCI-E x2, we want to know how much of a performance hit there is by running a M.2 drive at PCI-E x2 versus PCI-E x4.
Second, there have been reports online that M.2 drives run much hotter than standard SATA drives. What we want to find out is exactly how hot they run so we will know if we need to address any cooling concerns.
Finally, we want to know which of our current motherboards support booting to M.2 drives. M.2 should work as a secondary drive on almost any motherboard, but many users online have reported problems booting to M.2 drives.
For our qualification we will be using two different M.2 drives. The first is a 256GB Plextor PX-G256M6e which uses a Marvell PCIe 9183 controller that can utilize PCI-E x2. This drive is advertised to be able to reach sequential read speeds of 770MB/s and sequential write speeds of 625MB/s. The second drive is a 512GB Samsung XP941 which uses a proprietary Samsung controller that can utilize PCI-E x4. Because of the extra PCI-E lanes, this drive is advertised to be able to reach sequential read speeds of 1170MB/s and sequential write speeds of 930MB/s. This is over twice as fast as any SATA-based SSD currently available!
For our performance and thermal testing, the M.2 drives were configured as secondary storage devices so that the OS would not impact our benchmarks. For the motherboard qualification section, we used the drives as the primary drive in order to determine if the motherboard was able to boot to the drive.
Since the Asus Z97-A's onboard M.2 slot only supports PCI-E x2 and most of the other motherboards simply don't have a M.2 slot, much of our testing was done using a M.2 to PCI-E x4 adapter. We chose to use an adapter made by "Bplus Technologies" since it includes a heatsink to help cool the drive - and as you will see later in this article, having a heatsink for M.2 drives is a very good idea.
M.2 drives can operate in either SATA, PCI-E x2, or PCI-E x4 mode depending on what both the drive and M.2 slot support. Currently, most M.2 slots that are found on motherboards are only able to support PCI-E x2 which should be a limiting factor for faster M.2 drives. The big question is how much of a performance loss you will see by using an onboard PCI-E x2 slot versus PCI-E x4.
To determine the performance difference, we configured the M.2 drives as secondary storage drives and ran benchmarks using CrystalDiskMark with the default settings (5 passes with 1000MB files). We first installed the drives into the Asus Z97-A's onboard M.2 slot running at PCI-E x2, then installed the drives into a M.2 to PCI-E x4 adapter to benchmark them at PCI-E x4 speeds.
In terms of transfer speeds, at PCI-E x2 the Samsung drive is faster than the Plextor drive (especially in terms of write performance), but it is definitely being bottlenecked. When we moved the drives to PCI-E x4, the Samsung drive saw about a 50% sequential read performance increase and about a 25% sequential write performance increase. The Plextor drive, on the other hand, saw no benefit by using PCI-E x4 over PCI-E x2. This is to be expected since the drive itself is only designed to use two PCI-E lanes, but it is nice to see the benchmarks match our expectations.
To summarize, the Plextor PX-G256M6e (which is a PCI-E x2 drive) doesn't see much performance benefit by installing it in a PCI-E x4 slot, and in some cases it actually ended up performing a bit worse. However, the Samsung XP941 (which is a PCI-E x4 drive), definitely needs all four PCI-E lanes in order for it to run at peak performance.
We have seen some reports online of M.2 drives (specifically the Samsung XP941) running very hot, so we wanted to see for ourselves how hot both the Plextor and Samsung drives run. Unfortunately, these drives do not have any thermal sensors integrated that we could find so we were limited to using a thermal camera to find the hottest point on the top of the drive. This is not 100% accurate since there may be hot spots on the back of the drive but it is about as accurate as we can get with current M.2 drives.
Since idle temperatures are not a great indication of how cool a device runs, we wanted to load the drives using a real-world scenario. To do this, we placed roughly 103GB worth of ISO files on the drive and made a 1:1 copy of those ISO files while recording a video of the drive using a thermal camera.
As you can see, both of these drives run very, very hot. To be clear, we weren't doing anything crazy (just making a copy of a bunch of ISO files) yet both drives quickly got up to temperatures that we are not comfortable with. One thing we want to point out is that the actual storage chips are not what is getting really hot, but rather all the other chips on the drive like the controller chip. On the Samsung XP941 the controller is on the top of the drive so the thermal camera can directly see that it got to 113 °C. However, on the Plextor drive the controller chip is on the back of the drive where the thermal camera cannot see it. It is entirely possible that the Plextor drive is actually running much hotter than the 94 °C we recorded since the controller is not directly visible to the thermal camera.
There are rumors of LSI and Marvell coming out with new, more efficient controllers in the near future so hopefully that will allow M.2 drives to run at a more reasonable temperature. Until M.2 drives are able to run cooler, however, we recommend using M.2 slots that are integrated onto a motherboard only if you are able to check the drive temperature to make sure it isn't overheating. Otherwise, we recommend using a M.2 to PCI-E adapter that includes a heatsink like the one we used in our testing. In fact, when using the heatsink the temperature on the Samsung XP941 dropped down from 113 °C to a maximum of about 53 °C which is a much, much safer temperature.
Since M.2 is a completely new storage specification, we wanted to do fairly extensive testing to determine which motherboards support M.2 drives. One thing we quickly found was that while every motherboard we tested can see both the Samsung and Plextor drives just fine as secondary storage devices, there we some problems using them as primary boot drives.
Due to this, we decided to test the majority of the motherboards in our current product line to determine which boards support booting to M.2 drives. Our testing consisted of simply installing Windows 8.1 in both BIOS and UEFI mode and seeing if the board would boot to the drive. There are some reports online that you can make a M.2 drive bootable by making it a single disk RAID then installing in UEFI mode, but what we are primarily interested in is which motherboards support booting to M.2 drives without having to go through a ton of extra hoops.
With the exception of the Supermicro H8QGi-F (which doesn't support UEFI), we were able to install and boot to the Plextor PX-G256M6e in either BIOS or UEFI mode on every motherboard we tested. Unfortunately, the Samsung XP941 isn't quite as widely compatible. In fact, the only motherboards we could get to boot to it were ones with either a Z97 or H97 chipset. Interestingly, these are also currently the only chipsets that include native M.2 support.
Even though we only tested a limited number of motherboards, our testing indicates that it is very likely the Plextor drive will work as a boot drive on nearly any modern motherboard while the Samsung drive will only work on newer chipsets that include native M.2 support. We did only test Asus and Supermicro boards, however, so if you have a different motherboard brand we recommend contacting the manufacturer and asking them which M.2 cards your motherboard will support booting to before purchasing a M.2 drive.
M.2 is interesting because it has some very distinct pros and cons, but the pros are muddied by the fact that not all M.2 drives are even close to each other in terms of performance. The biggest advantage to M.2 by far is the performance possible by using the PCI-E bus rather than a SATA controller. The Samsung XP941 very clearly shows this with its amazing transfer speeds that are over twice as fast as any SATA-based drive currently available. However, since M.2 can use either SATA, PCI-E x2 or PCI-E x4 there is a wide range of performance possible from a M.2 drive. The ones that use SATA likely won't be any faster than current SATA SSDs and like we saw from the Plextor PX-G256M6e, PCI-E x2 drives will likely only be about 30% faster than SATA SSDs. This is nothing to scoff at, but it means consumers will have to pay close attention to a drive's specifications when purchasing a M.2 drive.
Another advantage to M.2 is that you can use a very simple M.2 to PCI-E adapter to add one or more M.2 drives to your system. What we haven't touched on is the fact that an adapter card doesn't have to be limited to a single M.2 drive. While not available right now (that we can find at least) we completely expect someone to come out with a card that adapts four M.2 drives to a single PCI-E x16 slot. This would give you a ton of versatility since you could install four individual M.2 drives into a single motherboard slot or you could RAID the four drives together in a RAID0. Theoretically, this could allow for transfer speeds of up to 8GB/s which would almost match the performance of DDR3-1066 system RAM!
While the performance implications of M.2 are amazing, they certainly come at a cost. First, current M.2 drives run very hot. 113 °C on the Samsung drive and 94 °C on the Plextor when doing a few minutes worth of file copies is simply not acceptable. Luckily, there are M.2 to PCI-E adapters available that include heatsinks to help cool the M.2 drive. If you are using a M.2 slot on a motherboard, however, we recommend you keep a close eye on it to make sure it doesn't get too hot.
Finally, motherboard compatibility is not universally very good right now. The Plextor drive worked as both a storage and boot drive in every motherboard we tested, but the Samsung had problems booting on the majority of the boards we tried it on. Unless you have a Z97 or H97 motherboard, don't expect to use a Samsung XP941 as anything other than a storage drive.
Overall, M.2 is a very exciting technology. Potential performance is phenomenal and the current problems can all be worked around through the use of M.2 to PCI-E adapters and limiting your choice of motherboards if you want to use a Samsung XP941 as a boot drive. However, what we are even more excited for is the M.2 controllers LSI and Marvell are rumored to be working on that are supposed to be much more efficient than the current M.2 controllers. If this is true, we expect to see even better performance, reduced temperatures, and much better motherboard compatibility in the near future.
I'm interested in getting a Z97 Gryphon with the XP941, but I see that the Gryphon has no m.2 slot. According to this article, you were able to get the SSD to boot in that motherboard. What steps did you take? Thanks.
All we had to do was install to the drive in UEFI mode and make sure we had the latest BIOS. Before the recent BIOS files Asus published, you had to do weird things like installing the drive as a single disk RAID. As far as we can find, this is no longer necessary.
If you are unfamiliar with UEFI, you first need to make sure UEFI is enabled in the BIOS by going to the "Boot -> CSM(compatibility support module)" (this page: https://www.pugetsystems.co... ) and making sure everything is set to either "Legacy and UEFI" or "UEFI only" (it should be in Legacy and UEFI by default). Then, make sure to boot to your install media using the boot device that includes "[UEFI]" at the start of the device name. When you boot to the media as a UEFI device, Windows will automatically install in UEFI mode.
Once the OS is installed, you will notice that there is a new bootable device in the BIOS called "Windows Boot Manager". This is what you actually want to boot to.
Does this mean that the my plextor PX-G256M6e SSD isappearing is caused by overheating? or can it be a defect and is RMA-able? does the drive throttle itself on high temperature?
Most likely it is simply defective, but if you have very little airflow in your chassis it is possible that it could be overheating. We actually just got a response from our Plextor rep about safe temperatures and they say that the controller (which is what is getting really hot) is rated for up to 125C. The memory itself should only get to like 80C, but from our testing never gets anywhere near that.
i actually have a asus maximus vii hero.... and was planning on using the m.2 slot, but after your review.. im thinking of trading the hero in for a formula and waiting for the asus express m.2 to x4 adapter card when it comes out.. which will give me full speeds aswell.
Yea, we used the adapter card to boot on Gryphon. Actually, we used it on everything, we just also tested the onboard slot on the Z97-A and H97I-PLUS. After doing all this testing, I'm pretty sure that what makes a M.2 bootable or not isn't the adapter card at all, its the controller integrated onto the M.2 drive itself. From the motherboard and operating systems's point of view, there is really no difference between an onboard M.2 PCI-E slot and the normal PCI-E slots. So whether you will be able to boot to a M.2 drive should depend almost entirely on the M.2 drive's controller.
Whether you keep the Hero board or switch to a Formula, either one should support booting to the XP941 in Windows 8.1 as long as you install in UEFI mode. We haven't tested either, but they both use the Z97 chipset. And since the Z/H97 chipsets are the only ones that worked I would say you have a pretty good chance of it working.
yeah looks like u made it a little more difficult to find one... lol they was all on amazon yesterday..... but no worries.. i just went straight to the source... Bplus M2P4A... just ordered one... i seen some generic one's on amazon.. but the build quality just didnt look as good .. especially the heatsink that was on the generic..
do u think there will be any problems with this on the formula in the 3rd slot with two 780ti's in sli above the adapter?
It should work fine in the third x16 slot. The only downside to using that slot is that it shares bandwidth with the Sata Express connector. So you won't be able to add a SATA Express drive in the future. Personally, I don't see SATA Express taking off so I wouldn't be too worried about that.
cool... thanks again for taking the time to respond.. and once again great review..
Technically, why Samsung disk not boot on "not z97 or H97" motherboards, but the Plextor disk boot on every mb and chipset?
The reason the Samsung drive does not boot on most motherboards is because the controller simply doesn't have the files needed to be a bootable device while the Plextor does. Z97 (and H97) as a chipset natively supports M.2 drives, however, so by installing in UEFI you can essentially bypass the requirement of having those boot files integrated into the controller.
I've been trying to get a Plextor M6e (512 GB) installed into my A97 Deluxe for the better part of the week and Intel RST won't see it. My original setup is using an Intel 530 m.2 which I believe is inherently SATA, and Intel RST sees it without any fuss and allows me to set up a 64 GB cache as well as leaves the remaining space for a simple partition or whatever. What gives with the Plextor? Plextool won't let me secure erase because it reports back that the SSD is "froze locked". I've read that Intel RST will not allow the use of an Acceleration Cache on an SSD with data on it and if you secure erase the SSD, then Intel RST will play nice. From what Plextool shows, there's some 55 MB of info on this card even when all partition info is removed with the Windows Disc Management console. I've also disabled all the Secure Boot functionality built into the Asus BIOS. Still no worky.
I've never tried to make a M.2 PCI-E drive a cache, but if it is just that it needs to be secure erased than it shouldn't be too bad. The frozen error is a normal error you will get when trying to secure erase any newer SSD. When you get that error, you can try putting the system into standby, waking it up, then trying it again. On normal SATA drives you could pull the SATA power cable for a few seconds then reconnect it and it would unfreeze the drive, but M.2 is more complicated since it isn't as easy to just cut the power. If that doesn't work, I would contact Plextor support to see what they recommend doing.
However, I would encourage you to think about whether making the drive a cache is the right approach. I'm guessing this is for your OS drive, and with a 512GB SSD we usually recommend to just install the OS directly onto the SSD instead of making it a cache drive. Caching only improves program launch speed, but having the OS directly on the SSD improves everything related to read and write.
i dont understand one thing.... is this adapter conected to a pci express 3.0? can it be connected to a pci express 2.0 with same performance? ...... so..... the question ....can i connect this ssd m.2 x4 to a pci express 2.0 on an 990fx amd motherboard and expect the same performance?
We actually tested that, but left out of the article because we didn't want the article to get too complicated. To answer your question, we saw a very tiny increase in performance with a PCI-E 3.0 slot, but it was only a couple MB/s. In other words, well within the margin of error for this kind of testing.
However, this is only for these drives which are rated for PCI-E 2.0 . If drives come out in the future that are rated for PCI-E 3.0 I would expect them to perform better in a PCI-E 3.0 slot.
Did you find the same heat issues when using the drives with the onboard M.2 slots? I would like to do a small build like your Echo 1 using the Asus H97I-Plus, but I'm a little concerned that the drive will be sitting sandwiched between the board and the back of the case, so there would be little ventilation.
Yes. Due to that, we're not currently selling the XP941 in any onboard M.2 slots -- only in the PCI-E slot sled that includes a heatsink. The Plextor M6e does just fine though.
Do you know if the SATA based drives also run hot? The specs listed for the H97I on the ASUS website seem to indicate it will run the M.2 slot in either SATA or PCIe mode. For this particular system, the speed bump from running in PCIe mode is not really needed. I mainly want to keep it cool and minimize cables, so using the M.2 slot is attractive. Thanks.
We didn't test any SATA drives for this article, but we have used them in the past. I don't expect you'll have any heat issues whatsoever with a SATA based drive. They're a lot slower, and the controllers are a lot more mature and able to keep up with those speeds.
We are planning to upgrade a notebook Acer VN7-791G-70BU (V Nitro 17 black edition) installing Plextor PX-G256M6e M.2 2280 SSD 256 GB.
"Intel 8 series/C220 series PCI EXPRESS root port #3 - 8c14"
"Intel 8 series/C220 series PCI EXPRESS root port #4 - 8c16"
"intel Xeon processor E3-1200 v3/4th gen core processor PCI EXPRESS x16 controller . 0c01"
I've been reading about PCIe SSD's for days, trying to find facts rather than a lot of speculations on if they work as a boot drive, especially the samsung xp942, which I'm considering buying for my new build. I can't thank you enough in succinctly sorting out the 'wheat from the chaff'... and showing us the results of your findings. At least now I can go ahead and buy a Z97 mobo and put it with this SSD and use it to boot.
Does any Z97 mobo work to use this XP941 as a boot drive, as long as it has the PCIe x 4 or M.2?
I'm taking from your article, that an SSD adaptor into the x4 slot is the best way to achieve optimal read/write speeds regardless if it has an M.2 slot.
Just in case something got released that we don't know about, you mean the Samsung XP941, correct? For that drive, we have not yet seen a Z97 motherboard that did not work with it as a boot device as long as the OS is installed in UEFI mode. If it has anything less than a M.2 x4 slot, however, you are right that you would want to use a M.2 to PCI-E adapter in order to get full performance. In fact, with the XP941 we would suggest getting a PCI-E adapter with a heatsink (like the one we used in this article) due to how hot the XP941 gets and not even plan on using an onboard M.2 slot if at all possible.
Edit: Just want to add a quick disclaimer - we've only tested Asus and ASRock Z97 motherboards. While I would assume any Z97 board should work fine, I can't speak from experience for other brands like EVGA, Gigabyte, MSI, etc.
When you installed the XP941 into the bplus m.2 pcie adapter, was there any space between the heatsink and the actual chips of the ssd? When I went to install the heatsink on mine, I noticed there is a small gap that prevents them from actually touching. It's a very small gap, nothing big.. but still not technically touching. Wondering if thats ok?
You know, thats actually something we've started seeing on some of the bplus adapters. Sometimes it is fine, sometimes there is a gap. What we are doing is using an additional thermal pad between the ssd and the heatsink. Thermals might be slightly higher than if the heatsink was making direct contact, but the difference is actually much smaller than you would expect.
This is what we are using: http://koolance.com/thermal... . You probably don't need anything that large, but the price is actually pretty competitive compared to other quality thermal pads.
ah. good idea. I also noticed the little red rings that slide over the screws are kinda thick on one side. I wonder if removing those would allow the heatsink to make proper contact? Think they should even be there?
Yea, you could try that too. I don't think there should be a problem with the heatsink shorting anything if it comes into direct contact with the PCB, but you might want to use something in place of those washers just to be safe. A few layers of tape with a hole poked in it would prevent any possible shorting and would be thinner than the red washers that comes with the heatsink.
Do you usually find the 0.5mm thermal pad is usually enough to close the gap? Or do you use a thicker size as well?
We've only ever seen a very small gap, so for us the .5mm has been enough.
ah. yea. I'll have to check when I get home, but if I recall, the gap is only paper thin for me as well. Good suggestion. Another idea I had was to get some thin cardboard to replace the thick red rings. That way, the board is still protected from having the heatsink metal rub against it.
Did you end up putting the thermal pad on both the memory chips and the controller chip? I noticed on mine, the memory chips are actually higher than the controller chip, so If I put a pad covering both, then the controller still has a gap stuck in it.
I believe we just put it across the controller chip since that is the only thing that actually gets really hot.
By any chance, have you checked the SMART status of these drives in a utility like Crystal Disk Info?
I noticed on my first drive it says "Used Reserved Block Count (Total): 2E7" which from my understanding means it found "hex 2E7" worth of bad blocks and remapped them. Concerned, I RMA'd my first drive and noticed my second one says the same thing but with "833" blocks this time! Wondering if this is normal for these drives or did I just get stuck with two duds?
Great article, cleared up a lot of confusion for me. If I understand correctly, you've been able to boot from the XP941 in UEFI mode using the M.2 to PCIe adpater on a H97 motherboard.
So my question is, will I be able to boot using an adapter?
If so, which of these slots do you recommend using to get maximum performance from the XP941?
It should work as a boot device on your motherboard, but that exact model isn't one we use so I can't 100% guarantee it. As for which slot to use, I would definitely recommend the 1 x PCIe 2.0 x16 (max at x4 mode, black) slot. The PCIe-x1 slots will really reduce the performance of the drive (since it is a PCIe x4 drive) and the 1 x PCIe 3.0/2.0 x16 (x16 mode, gray) is needed for your GPU.
Yes, this means you won't be able to do dual GPU in the future, but it really is the only open slot on that motherboard that will give you full performance from the XP941.
Thanks a lot, Matt! Took me a while to find this kind of comprehensive information on this subject.
So I take it that the Gigabyte GA-Z97X-UD7 TH motherboard I just got is not compatible with an xp941 x4 without an adapter. And an adapter will cause overheating and loss of speed? If it works at all?
I can't speak directly to that Gigabyte motherboard, but we have found the PCI-Express x4 adapter cards with heatsinks to work very well in terms of cooling the Samsung M.2 SSDs and letting them run at full speed.
Thanks for a quick answer. What about after booting in UEFI with this SSD, I would lose all access to my SATA drives?
We don't have any experience with the X99 Pro specifically - we use the X99 Deluxe mostly. We have found that one some motherboards using a PCI-Express based SSD as the C: drive requires turning off sleep mode in Windows.
thanks, now , what are folks doing with these smaller ssd when windows 8 loads all of the win8 apps on the main c drive. From the store, you are not given any choice on where to install apps. Even some desktop programs dont ask any more. These smaller ssd will fill up. etc. DO folks move their Library folder or redirect to another drive.
Thinking might be better to use standard ssd like the 1Tb 850EVO rather than trying to out fox windows on where it install things.
How on earth do folks use these small 128 or 256 ssd as main drive when you cant tell where you want to install software.
It all depends on how much storage space you need. I have a 120GB SSD at work, and a 240GB on my main system at home - and so far both have been large enough. My home system did start out with a 80GB drive about five years ago, and then moved to a 120, and finally a year or two ago to the 240GB I use now. I think a ~250 - 500GB SSD is fine for most folks, especially if you have (or add later) additional hard drives.
Thanks. Thought that might be right, but still trying to figure out why MS wont let us pick where to install the metro apps. I dug around on net and found how to do it, but of course it takes digging into the registry etc. so not useful. Should be allowed to choose. I have 3 xtra internal HD and 1 external hd, but as said....some progs dont give you option to install somewhere else. Just install on C: with no option for somewhere else.
Yes, we found that putting them in the adapter cards - which include a heatsink - was much better in terms of temps.
thermal performance of SSDs in the M.2 socket.
any insights as to the temperature of the SSD without the heat sink.
to add a quick disclaimer - we've only tested Asus and ASRock Z97 motherboards.
Great info here....what thinking on using an ASUS X99 Pro mobo with this 941 as boot drive. ASUS compatability sheet says 941 is compatible...need it to be C: boot drive. any guesses if it will work without bunch of messing. Can I just load from the Win 8.1 pro.
Test: Copy the Programs Files (x86) folder from the C:\Programs Files (x86)\ to C:\temp\Programs Files (x86)\. The folder contained 117GB, 106,435 files and 3676 folders. A handheld infrared thermometer was used to take the temperature readings.
socket connected directly to the CPU PCIe bus and bypassing the Z97 chipset.
RESULTS: It took 7:39 minutes to copy the 117 GB of files. This was considerably longer than the 4:39 minutes it took in the articleâ€™s test to copy the 103 GB of ISO files. Presumably, this was because my test used many smaller files. The maximum temperature reached in any part of the Samsung XP941 was 95 Â°C at 5:36 minutes into the test. The Samsung XP941 then cooled rapidly similar to the results in the articleâ€™s video.
CONCLUSION: The Samsung XP941 operates at between 40Â°C to 50Â°C during normal operations. I have been taking occasionally readings of the SSD as it sits on my desk with the case opened over the past week. I have decided to go ahead with this setup and with no heat sink (as none is available for the SSD mounted directly to the motherboard M.2 socket). The performance is very good. It takes Windows 7 about 4 or 5 seconds to boot after BIOS is complete. I have installed all my software I on the Samsung XP941. I use a separate 3TB RAID 1 HDD for data. I give the Samsung XP941 4.5 stars (out of 5). I would like it cooler and would like the next Samsung M.2 PCI Express Gen3 (Gen 2 is all us mortals can get now) to get the last half star.