Intel Core i7-7740X Review


The Bottom Line

Intel's "Kaby Lake" i7 chip on the Core X platform delivers good quad-core performance in line with the Core i7-7700K, but lacks extra PCI Express lanes or other standout features. Most users should stick with Intel's mainstream platform, or opt for a Core X chip that's a little more expensive.



  • High base clock speed.
  • Much more affordable than higher-end Core X-Series CPUs.
  • "Kaby Lake" base architecture means better support for 4K streaming than on higher-end "Skylake X" CPUs.


  • Similar performance to the Core i7-7700K, but on a pricier platform with costlier motherboards.
  • Only 16 PCI Express lanes on the CPU.
  • Six-core Core X chip costs just $50 more, supports more lanes.

2017 has been a busier year in the desktop processor market than, arguably, the last few years combined. And as we write this in late June 2017, we've still got half a year to go, with plenty of new chips on the horizon from both AMD and Intel. Let's take a quick look at how we got here and where things are going.

Image: Intel Core i7 Box.jpgAMD's FX processor line, which debuted with the AMD FX-8150 way back in 2011, was serviceable and long-running, but it never offered Intel much competition above the Core i5 level. Because of this, Intel was able to shift its focus to power efficiency for the larger laptop market without the need to protect its flanks. And as a result, particularly in the last few years, its raw compute-performance gains have been modest (to put it mildly) from one chip generation to the next. Sure, Intel stepped things up in 2016 with the 10-core Core i7-6950X Extreme Edition, but that chip was priced at a wildly high $1,700 or so.

But then, early in 2017, AMD burst back into high-end consumer CPUs with its Ryzen processors, headed by its top-end eight-core Ryzen 7 1800X, and the arguably more impressive (from a value standpoint) six-core Ryzen 5 1600X. The Ryzen chips are far more efficient and powerful than the company's previous-generation FX parts. And they deliver as many as 16 threads of compute performance at prices that are sometimes just half of Intel's similarly outfitted competition. Not content to stop there, AMD also announced it would soon offer up a 16-core, 32-thread CPU, as part of its upcoming "Threadripper" enthusiast-chip lineup, which the company says we should see sometime this summer.

That brings us to today, where, at least partially in response to this newfound competition in the enthusiast space, Intel has rolled out the first of its "Skylake X" and "Kaby Lake X" lineup of Core i9, i7, and i5 processors, collectively known as the "Core X-Series." We haven't yet laid hands on the top-end Core i9-7980XE; Intel says that chip won't arrive until sometime in October. But we did recently take a long test-drive with the 10-core Intel Core i9-7900X. It outperformed last year's $1,700 Core i7-6950X Extreme Edition 10-core chip at a more reasonable (though still unquestionably expensive) $999. Like all the chips in Intel's new Core X family, it will require a new motherboard with a new socket, called LGA 2066. Socket 2066 supplants the LGA 2011 sockets of the last few generations.

Image: Intel Core i7-7740X.jpg

Now, if you ignore the price, a new 20-thread processor is unquestionably exciting. But Intel also introduced a couple of interesting additions to the Core X-Series lineup for those looking for more modest Core X chips alongside the Core i9-7900X and Core i9-7980XE. Based on the company's latest 7th Generation Kaby Lake architecture, the Core i5-7640X and Core i7-7740X (the latter of which we're looking at here) both sport four cores and drop into the same LGA 2066 socket/X299 motherboards as the higher-end Core X parts.

The Core i7-7740X stands out for its inclusion of Intel's thread-doubling Hyper-Threading technology, along with a high base clock speed of 4.3GHz. In terms of cores, threads, and clock speed, this chip is quite similar to the Core i7-7700K we looked at last year, which is the top-end chip in the company's mainstream processor line (which uses the LGA 1151 socket). And indeed, it's expected to sell for a similar price as the Core i7-7700K: $339.

Is this an ideal chip for gamers and enthusiasts who don't often perform core-hungry tasks like high-end video editing, but want to climb aboard the Core X-Series train? To find out, we'll have to pick apart some of the platform's more complex particulars. But it's worth noting that, with 16 lanes of PCI Express on the processor and 24 on the X299 chipset, there's no real bandwidth advantage for things like multiple graphics cards and NVMe solid-state drives with this chip versus the Core i7-7700K.

Also, bear in mind that the AMD Ryzen 5 1600X offers two more cores and four more computing threads for about $110 less. We'll have to see in our Performance section if the Intel chip's higher clock speed gives it a serious advantage.

Meet the New Core X-Series

Topping out with the Core i9-7980XE—which, when it debuts, will be able to tackle up to 36 compute threads at once—the new Core X-Series of chips goes above and beyond what we've seen from any Extreme Edition processors to land in our test beds in the past decade.

The Core i9-7980XE, in fact, is the first CPU to bring more than a teraflop of compute performance to the consumer-computing table. That's the kind of performance metric we're used to seeing on graphics cards, not CPUs.

Image: Intel Core X Boxes.jpg

As we noted above, along with the highest-end chips, Intel will also bring a pair of "lesser" Core i7 and Core i5 processors—using the Kaby Lake architecture—to the new platform, using the same new LGA 2066 socket. Here's a list of the company's new chips, direct from Intel. Note that Intel is keeping many of the details of the upper four Core i9 chips under wraps for now, thus all of the dashes below. The company says these top-end Core i9 CPUs will arrive between August and October. Among the i9 chips, only the Core i9-7900X rolled out with the initial Core X-Series launch.

Image: Intel Core X-Series Specs.png

Now, if you're looking at pricing, you'll notice that the top end 18-core Core i9-7980XE commands a whopping $1,999. (At least, that is per 1,000 units, which is how Intel has long listed pricing for its highest-end CPUs, although retail pricing is usually about the same). Clearly, Intel isn't worried that much about AMD at the top end of the stack. (And keep in mind that as of this writing, we still don't know how AMD will price its competing Threadripper chips.)

But if you take a look at the 10-core Core i9-7900X, you'll notice that at $999, it's priced about $700 less than the previous-generation Core i7-6950X. So while prices are still fairly high, progress is clearly being made on the threads-per-dollar front. And Intel is offering many more options on the very high end than ever. So there's no need to step up to (or even close to) the $2,000 range unless you absolutely need all the threads you can get. More choices are a good thing, and it's likely we have them on the Intel side, at least in part, because of what AMD has done so far this year.

Image: Intel Core X Boxes.jpg

On a related note, the eight-core, 12-thread Core i7-7820X, which will likely be the most direct competition to AMD's top-end Ryzen 7 chip, is priced at $599. That's $150 or so more than the current going rate for a Ryzen 7 1800X, but a whole lot more affordable than the $1,000 price of the previous-generation eight-core Core i7-6900K. Clearly, Intel is making an attempt to reclaim some of its core-per-dollar value over AMD, while maintaining some price premium over its desktop-chip competitor. It's not waging all-out price war.

The other interesting difference with the Core X launch is that, for the first time, the company is bringing two chip architectures (or at least two generations of silicon) to its enthusiast platform at the same time. The highest-end chips here are based on 6th Generation "Skylake" silicon, while those at the bottom of the above chart, the Core i7-7740X we're looking at here and Core i5-7640X, are actually based around 7th Generation "Kaby Lake" architecture, the same as you'll find in Intel's current top-end mainstream CPU, the Core i7-7700K.

That's important for a couple of reasons, but on the feature front, it means the Kaby Lake chips will support 4K HEVC encoding and decoding at 10-bit depths, as well as VP9 decoding. What's this mean in non-geek-speak? You'll need a chip from the Kaby Lake line (or later) if you want your system to support 4K streaming content from most major video outlets, or if you plan to, at some point, connect a 4K Blu-ray drive. A Skylake chip (even the 18-core beast) can't handle that kind of content.

We'll have a review of the Core i5-7640X (which sheds Hyper-Threading support and a few hundred megahertz of clock speed for a lower price) in the coming days. So stay tuned if you're intrigued by the Core X platform, but are looking for something more affordable.

CPU PCI Express Lanes & Chipset

The other major new wrinkle that arrives with Core X has to do with PCI Express (PCIe) lanes, which you can think of as the highway that shuffles bandwidth-hungry data between the processor and things like graphics cards and fast NVMe solid-state drives. Intel's enthusiast platform has long offered more lanes directly to the CPU than "lesser" chips like the Core i7-7700K. For instance, the now-last-generation Core i7-6950X supported up to 40 PCI Express lanes, while the Core i7-7700K has just 16.

But while those higher-end Skylake X chips, like the Core i9-7790X, get oodles of extra lanes, the Core i7-7740X and Core i5-7640X (the two current Kaby Lake processors in the Core X line) make do with the same 16 lanes as the similarly priced chips on Intel's mainstream LGA 1151 platform.

Here's a look at how some of the features break out between Skylake X and Kaby Lake X processors, compared to the features of Intel's previous-generation high-end desktop platforms...

Image: Intel Core X Platform Details.jpg

Now that the Core X platform spans two generations of silicon and ranges from a somewhat modest four-thread Core i5 chip to (eventually) a $2,000, 36-thread monster, the amount of PCIe lanes on the platform is a lot more complicated. For now at least, the two "entry level" Core i5 and i7 chips will offer 16 lanes, like their counterparts on the more mainstream platforms (like the Core i7-7700K). Stepping up the stack to the more midrange chips in this high-end platform, the Core i7-7800X and Core i7-7820X both offer 28 lanes of PCI Express bandwidth, and the Core i9-7900X offers 44 lanes. The extra four lanes over the previous generation is there on the high-end chips, ostensibly, to make sure builders have the bandwidth to consider Intel's new Optane Memory caching drives and eventually full-size Optane SSDs. Interestingly, Intel is still keeping the number of PCI Express lanes available on its upcoming highest-end chips under wraps for now. But it's a safe bet that they'll have 44 lanes or more.

If you're wondering what you (or, say, someone who wins a PC-hardware lottery) might actually do with all those PCI Express lanes on the CPU, Core X introduces another feature that could be quite bandwidth-hungry: VROC. Virtual RAID on CPU (VROC) lets you run multiple PCI Express/NVMe storage drives together in your choice of RAID flavor, directly through the CPU. Technically, the feature supports pairing up to 20 drives together in this fashion for a theoretical throughput of up to 128GB per second (and yes, that's big-"B" gigabytes).

Before we dive into further details of VROC, note that Intel has yet to announce VROC details officially. Everything we learned about this feature came secondhand from motherboard makers at Computex 2017. So take this with a grain of skeptical silicon, and know that things may change when Intel reveals final, official specs and details about this feature.

Image: Intel Core X (Back).jpg

Previously, on the consumer side of the CPU fence, you'd need a hardware RAID card to do something like a VROC setup. But as we'll see, there are quite a few caveats here.

First off, you'll need one of two Intel-provided hardware dongles plugged in to your X299-based mainboard to run drives in any configuration other than RAID 0 (striped). And we were told those dongles would cost $100 or $200 respectively, depending on what type of RAID you planned on running. This is probably an attempt by Intel to keep enterprise customers from saving some money by using consumer boards and processors to run tasks that are designed for server-class boards and Xeon processors.

Second, you'll need one of the Skylake X chips (like the Core i9-7900X we're looking at here) to use VROC. The Kaby Lake X chips lack the PCI Express bandwidth to make such a setup possible.

The final VROC caveat is the big one. At least for now, for your VROC RAID drive to be bootable, you'll need to run the array on Intel SSDs. Considering that it's Samsung's consumer drives (such as the Samsung SSD 960 Pro) that are generally the speediest, being forced to opt for Intel drives seems counter-intuitive if you're going all this way (and spending so much money) to get the fastest possible storage speed. Hopefully, a future feature update will allow non-Intel drives to be bootable in a VROC setup.

For the purpose of this particular review though, a crazy VROC setup isn't in the cards. Once you start plugging in more than a couple of PCI Express-bus x4 solid-state drives and a graphics card (or two), you're going to start running out of lanes and things will start disabling themselves on your motherboard. More on this issue soon.

Last on the feature front for Core X chips is an update to the company's Turbo Boost Max 3.0 technology. This tech debuted in the company's previous-generation Broadwell-E chips like the Core i7-6950X Extreme Edition. Now, instead of the chip being able to discern which one of its several cores is able to clock the highest and favoring it for certain tasks, Core X chips can choose two cores that get the Turbo Boost Max treatment.

Like the Extended Frequency Range (XFR) feature found on AMD's Ryzen chips (at least the models that end in an "X"), this is a good idea in theory. But it probably translates to a minimal appreciable advantage in overall performance, at best. Getting a couple of hundred extra megahertz in short-term bursts from one or two cores on a chip with eight or 10 isn't going to change how fast your system feels—unless maybe the "feeling" you're talking about comes from seeing sky-high but esoteric benchmark results. Regardless, it's moot here; Turbo Boost Max 3.0 is enabled only on the higher-end Core X processors. You won't find it on the Core i7-7740X that we're looking at here, or on the Core i5-7640X.

Along with the new chips and the new LGA 2066 socket, Intel will also be offering up a new X299 chipset to support it all.

Image: Intel Core X Platform Details.jpg

The chipset has up to 24 lanes of PCI Express hanging off the board. (Remember, this is in addition to the 16 lanes on the Core i7-7740X itself.) That's a big jump from the eight lanes available on the previous-generation X99 chipset, and it means X299 boards will technically support more SATA ports, USB 3 ports, and fast M.2 storage natively. If you're looking to connect all the things to your powerful PC, X299 should serve you well, provided you put one of the Skylake X chips in the board, which bring up to 44 extra lanes of bandwidth. But if you're company-agnostic, keep in mind that that AMD's Threadripper chips will reportedly have an even crazier 64 lanes of PCI Express on the chips themselves. (And not just the high-end chips, but all of them.) So long as Threadripper's performance can at least keep up, it looks like Intel will have strong competition in this high-end enthusiast space, as well.

Image: Intel X299 Feature Overview.jpg

The other wrinkle with X299 and Core X relates to memory. While the Skylake X chips support DDR4 memory running in quad-channel mode at speeds up to 2,666MHz (and higher when overclocked), the lower-end Kaby Lake X processors run in dual-channel mode (just like Kaby Lake chips do on Intel's mainstream computing platform). That means X299 motherboards will need to support both setups, and that you'll have to configure your RAM differently depending on what chip you have installed.

It also means the amount of RAM a board will support will vary depending on which chip you have installed. For example, here are the RAM specifications for the Asus Prime X299-Deluxe motherboard we're using as our testbed for Core X reviews...

Image: Intel Core X RAM Complications.jpg

As you can see, the DIMM support varies according to the Core X CPU core count. This setup also means, on a purely aesthetic basis, that you could end up with some strange RAM orientations, which could bother some builders with windowed cases and lighting. For example, on the above Asus board, when installing four DIMMs and a Kaby Lake X processor, all your RAM needs to be installed in the slots to the right of the CPU socket. That won't be a huge problem for most people. But for veteran builders and aesthetes, it looks and feels strange to have all your memory sitting on one side of the CPU with a bank of empty slots on the other side of the socket.

In summary, the Core X and the X299 chipset look to be powerful and well-equipped for all kinds of high-end hardware. But what exactly you can install in an X299 motherboard depends a whole lot on the exact Skylake X or Kaby Lake X chip you plan on putting in it. So, if you're planning a build, you'll want to spend some quality time with the manual of the motherboard you're considering, studying block diagrams and specs to make sure the parts you want will all work with the CPU you're planning on buying. And if you're planning on including more than a modest amount of bandwidth-hungry devices like PCIe SSDs and graphics cards, you'll probably want (or likely need) to opt for a Skylake X chip, not one of the Kaby Lake varieties that we're looking at here.

That's somewhat of an issue to our minds, because you effectively get the same serving of PCI Express lanes whether you opt for an X299 motherboard and a Core i7-7740X or Core i5-7640X (16 lanes on the CPU and 24 lanes on the board), or a Z270 motherboard and a Core i7-7700K (16 lanes on the CPU and 24 on the board). That makes the initial Kaby Lake Core X chips tough to argue for unless (a) you want a platform you can grow into, adding more components and a better CPU down the line, or (b) performance is better on the Kaby Lake X chips compared to their Core counterparts on Intel's mainstream LGA 1151 platform.

For the latter determination, we'll have to look at the benchmark numbers, of course. We'll do that shortly. But first, let's draw away from all of the backgrounder and take a closer look at the Core i7-7740X itself.

The Core i7-7740X: The Details

With the details about the platform and chipset out of the way, let's take a closer look at the Core i7-7740X processor specifically.

Image: Intel Core i7-7740 (Press Hero Shot).jpg

This quad-core, eight-thread chip's 4.3GHz base clock is very high, especially compared to the 3.3GHz base clock of the Core i9-7900X. But the Core i7's maximum stock Turbo Boost is just 200MHz higher, at 4.5GHz. That's not much of a bump as Turbo Boost upticks go, but it does match the top stock speed of the Core i7-7700K, making the two chips the highest stock-clocked silicon slices in Intel's current lineup.

That said, the Core i9-7900X can technically reach 4.5GHz under certain conditions with its Turbo Boost Max 3.0 tech, which the Core i7 chips lack. As such, both the Core i7 and Core i9 chips in the Core X lineup we've tested thus far effectively match the performance of the Core i7-7700K in lightly threaded workloads. In other words, while the Core i7-7740X is indeed in good company, you shouldn't expect it to break any performance ground, at least at stock settings.

Intel also rates the Core i7-7740X at 112 watts TDP (thermal design power, a measurement of heat dissipation). That's lower than the 140-watt-rated Core i9-7900X, but that chip has 2.5 times the cores of the Core i7. The Core i7-7700K, which runs on the same Kaby Lake architecture, has similar clock speeds and the same amount of cores, and it's rated at 91 watts. We're not sure where the extra 21 watts in Intel's rating is coming from. If anything, the Core i7-7740X should have a lower TDP than the i7-7700K, as the Core X chip lacks graphics silicon for gaming or just handling display output. With anything on the Core X platform, you'll have to provide a dedicated graphics card.

Performance Testing

For our test setup, we dropped the Core i7-7740X into the Asus Prime X299-Deluxe motherboard we mentioned earlier on, along with 32GB of Corsair memory running in a dual-channel setup (with all the RAM shifted to the right of the CPU, per the motherboard's instructions). An Nvidia GeForce GTX 1080 Founders Edition video card handled display output for our CPU-specific tests, and a Kingston HyperX Savage was the SATA-interface boot drive. We could have used a faster PCI Express/NVMe drive, but as we tested previous chips from Intel and AMD using SATA SSDs, we didn't want to drop in a speed demon and give the Core i7-7900X an unfair advantage. SATA SSDs like this one are still very respectable. We stuck all those components into Deepcool's GamerStorm Genome ROG Certified case, which includes a self-contained liquid cooler with a large three-fan radiator.

The chief competition for the Core i7-7740X is going to come from chips on more mainstream platforms. On the Intel side, that's the Intel Core i7-7700K, the Intel Core i5-6600K, and a couple of recent AMD chips, the six-core AMD Ryzen 5 1600X and the eight-core Ryzen 7 1800X.

To round out our charts, we also included numbers for the Core i9-7900X to show what spending a lot more on a processor will get you. And we lumped in the Core i3-7350K, which is unique for its high 4.2GHz base clock, its dual-core/four-thread arrangement, and the fact that it's unlocked for overclocking. The Core i3-7350K also sells for a modest (among this lot) $150.

Cinebench R15

First up in our testing regimen: Maxon's CPU-crunching Cinebench R15 test, which is fully threaded to make use of all available processor cores and threads, using the CPU rather than the GPU to render a complex image. The result is a proprietary score indicating a PC's suitability for processor-intensive workloads. Along with the usual test that makes use of all available cores, we've added the single-core results here to get a sense of how AMD's new chip fares in lightly threaded workloads.

Image: Intel Core i7-7740X (Cinebench).png

Things started out well for the Core i7-7740X, as on the single-core test it sat on top of (though, statistically, basically tied with) the Core i7-7700K and the Core i9-7900X. On the multi-core test, the six-core Ryzen 5 1600X did better nearly 24 percent better, though, and it sells for about $100 less.

iTunes 10.6 Conversion Test

We then switched over to our venerable iTunes Conversion Test, using version 10.6 of iTunes. This test taxes only a single CPU core, as much legacy software still does.

Image: Intel Core i7-7740X (iTunes).png

Music encoding doesn't exactly push a modern CPU to its limits, and certainly not ones like these. Again, the Core i7-7740X chip landed almost dead even with the Core i7-7700K and the Core i9-7900X here. The AMD Ryzen chips, while they aren't all that far behind, prove that Intel still has the advantage in lightly threaded workloads.

Handbrake 0.9.9

These days, our traditional Handbrake test (run under version 0.9.8) takes less than a minute to complete with high-end chips like these. (It involves the rendering of a 5-minute video, Pixar's Dug's Special Mission, to an iPhone-friendly format.) So, we've switched to a much more taxing (and time-consuming) video-crunching test that uses a nice, big hunk of 4K video.

In this test, we switched to the newer Handbrake version 0.9.9, and tasked the CPUs to convert a 12-minute-and-14-second 4K .MOV file (the 4K showcase short film Tears of Steel) into a 1080p MPEG-4 video…

Image: Intel Core i7-7740X (HandBrake).png

The Core i9-7900X, of course, dominated here, with its 10 cores. And once again, the Core i7-7740X and Core i7-7700K were quite close, though interestingly the latter pulled ahead here by a few seconds. And once again, the Ryzen 5 1600X did significantly better for about a third less money. The Core i7-7740X is not the best performer for the money when it comes to tasks like high-end media creation, where maximum cores and threads count.

POV-Ray 3.7

Next up, using the "All CPUs" setting, we ran the POV-Ray benchmark, which challenges all available cores to render a complex photo-realistic image using ray tracing. After that, again to get a sense of how the Core i9 handles single-core performance, we ran the same benchmark using the "One CPU" setting.

Image: Intel Core i7-7740X (POV-Ray).png

The performance trend continues here, with the Core i7-7740X about evenly matched with the Core i7-7700K, and coming out on top on the "One CPU" setting. But on the "All CPUs" setting, the six-core Ryzen 5 1600X pulled more than 20 seconds ahead, and again: while costing about $100 less than the Intel chip.

Blender 2.77a

Blender is an open-source 3D content-creation program that can be used to design and create visual effects, animation, and 3D models for use in video games or 3D printing. We open a standard test file (it's of a flying squirrel) and time how long the test processor takes to finish the render.

Image: Intel Core i7-7740X (Blender).png

The results here were all fairly close (save for the Core i3 and i5 chips), and the Core i9-7900X did best, as we'd expect. The two Core i7 CPUs also managed to pull an upset on the Ryzen CPUs here, although the Ryzen 5 did manage to stick close to its Intel competition.

7-Zip File Compression

Last, we fired up the popular 7-Zip file-compression software and ran its built-in compression/decompression benchmark, which is another useful test of a CPU's multi-core abilities.

Image: Intel Core i7-7740X (7-Zip).png

The 10-core Core i9 chip absolutely dominated here, doubling the score of the Core i7 chips. But interestingly, the Core i7-7740X managed to pull about 5 percent ahead of the Core i7-7700K. Perhaps the higher base clock speed and higher TDP of the Kaby Lake X chip provides some benefit. But again, if you're regularly performing tasks like this that take advantage of all available cores and threads, look at the Ryzen 5 1600X, which delivered about 10 percent better performance for more than $100 less.


Overclocking was an interesting experience when we tested the higher-end Core i9-7900X, in that high temperatures were the limiting factor with that 140-watt chip, not the system stability and lockup issues that are more typical when pushing a chip to its limit.

That wasn't the case with the Core i7-7740X, likely in part due to the fact that it has four cores to the Core i9's 10. But with a base clock of 4.3GHz, it's clocked very high out of the box, so we weren't sure how far we could push it, even with our Deepcool triple-fan liquid cooler. But in the end, we settled at 4.8GHz across all cores. Given more time to mess with voltage settings, 4.9GHz might have been possible on the cooler. But in a couple of hours of testing and tweaking, the chip was never quite stable when running our benchmark tests at that setting. But it ran rock-steady when stepped down to 4.8GHz. Of course, overclocking abilities often vary from chip to chip, so your results may vary.

At 4.8GHz, which is 300MHz over the chip's stock top Boost Clock setting, our Cinebench score jumped to 1,053 from 982 (at stock), an increase of 7 percent. On the POV-Ray test, the overclock resulted in a change from 2 minutes and 5 seconds on the "All CPU" test at stock, to 1:55 when overclocked. Again, that's a change of 6 or 7 percent. We wouldn't expect to eke out a whole lot more performance than that from this chip, as anything approaching 5GHz is very high for modern desktop silicon, unless you happen to get a very overclocking-friendly chip. Overclockers often achieve much higher results, but that's for short periods using exotic cooling substances like liquid nitrogen. If you actually want to use your CPU for productivity or gaming purposes, you'll have to settle for more modest clocks.

Gaming Performance

We don't ordinarily run graphics tests when testing processors without integrated graphics. That's mostly because graphics performance typically has much more to do with what graphics card you have installed than what processor you're using—especially when you're talking about a powerful chip like the Core i7-7700K.

But after testing AMD's initial run of Ryzen 7 and 5 chips, we noted they have issues keeping up with Intel's recent mainstream Core i5s and Core i7s at 1080p in games. Many other reviewers have, as well. Given this, and the fact that the Core i9-7900X has a high core count similar to the Ryzen 7 chips, we wanted to see if the Core X lineup had any similar issues. So we used the same Nvidia GeForce GTX 1080 Founders Edition card that we tested with the Ryzen chips to run a couple of the tests that we also use for graphics-card testing.

For comparison numbers, we did the same thing with our Intel Kaby Lake testbed running the Core i7-7700K. Both systems were tested using a Serial ATA-based SSD boot drive. The RAM in our Core X testbed was specifically running at 3,200MHz, the same speed that we used when testing the Ryzen chips, using the motherboard's built-in XMP profile. This is important because the Ryzen chips tended to perform better at 1080p with faster RAM. And after some initial testing running the RAM at lower (2,166MHz) speeds, we can say the same is true for the Core i9-7900X, as well. When we cranked up the RAM speed, frame rates went up modestly, as well.

Image: rise-of-the-tomb-raider-very-high-4k-benchmark.png

That said, the Core i7-7740X doesn't appear to have the same underlying issue. High core counts seem to be the prime factor in reduced graphics performance at 1080p, because at that resolution, both the Core i9-7900X and Ryzen chips delivered significantly lower frame rates than a similarly outfitted rig running the quad-core Core i7-7700K. And we're not talking a few frames per second (fps), either. The Core i9 and the Ryzen 5 and 7 chips turned in fps counts that were between 30 and 40fps lower than what the Core i7-7700K system delivered at the same 1080p resolution. But when we cranked the resolution up to 4K, effectively taking any CPU bottleneck out of the picture, performance evened out.

However, when we fired up our Core X test bed with the Core i7-7740X and ran our Rise of the Tomb Raider test in DirectX 11 mode at the Very High preset, we got a result of 136fps, which is slightly higher than the 128fps we saw on the same test with our Core i7-7700K system. Then we switched to Far Cry Primal, on the title's High preset. At 1080p in this benchmark, the Core i7-7740X turned in 138fps, 8fps higher than the 130fps that the Core i7-7700K managed on the same test and settings. On both tests, when we turned the resolution up to 4K (3,840x2,160), performance evened out, with both Core i7 chips on both platforms delivering between 47fps and 49fps on both tests. The same was true of the Ryzen chips at 4K.

What does that tell us? At least for these two test titles, Intel's Core i9-7900X exhibits similar performance issues to what we saw with AMD's Ryzen chips when paired with a high-end card running at 1080p. But the quad-core Kaby Lake X Core i7-7740X that we're looking at here doesn't appear to have the same problem. It delivered slightly better gaming performance at 1080p than the Core i7-7770K that runs our graphics-card test bed.

That makes the lower-end Kaby Lake chip a better choice for 1080p gamers than the Core i9 chip. But let's not forget: Even if you are gaming on a 1080p screen, the near-triple-digit performance we saw in testing with the Core i9-7900X is still very smooth. Down in the real world where most of us still game (in the 60fps range), what the Core i9 delivers, just as we said with the AMD Ryzen chips, is more than good enough for serious gaming.


After years of modest upgrades and clock-speed upticks, suddenly there are so many new, interesting, and impressively performing processors on the market (with plenty more to come) that it's becoming difficult to discern what a given chip is best suited for, or for whom.

That's where we find ourselves with the Core i7-7740X. For the most part, it performs similarly to the Core i7-7700K, which mostly impressed us when we reviewed it a little over a year ago. That chip is still a fine performer for gaming and productivity, as is the Core i7-7740X.

Image: Intel Core X Chip Flat.jpg

The thing is, the Kaby Lake X Core i7 chip doesn't offer the extra PCI Express lanes that the higher-end Core X chips do, even though you'll have to spend more on a motherboard to house it compared to a Core i7-7700K. When we wrote this in late June 2017, available X299 motherboards started at $220, with most priced above $250. Low-end Socket 1151 motherboards, meanwhile, start as low as $50, with Z270 boards (that's the top-end chipset for the platform) specifically starting at just over $100. That's a big price difference.

Then there's AMD's Ryzen chips to consider. The six-core Ryzen 5 1600X delivers six cores for appreciably better performance on multi-core tasks than this Kaby Lake X Core i7 chip for about $110 less. And AMD AM4 motherboards also start as low as $50 or so, with lots of appealing options in the $100 range. Sure, the Core i7-7740X does deliver better performance than the AMD parts at single-core tasks. But when was the last time you sat around waiting for any modern, reasonably powerful desktop chip to finish a single-core task? Any Intel Core or AMD Ryzen chip is effectively "good enough" for most users on that front these days. By now, most CPU-taxing, time-consuming tasks have shifted to multi-core processing.

With Intel's mainstream platform and a Core i7-7700K delivering similar performance and cheaper motherboards, and AMD's Ryzen chips offering up better multi-core performance at a lower price (also with the benefit of lower-priced motherboards), the Core i7-7740X is in a bit of a tough spot. If it had more than 16 PCI Express lanes on the chip, like the costlier Core X offerings do, it would be a nice alternative for gamers looking to get into the X299 platform with its support for super-fast VROC SSDs and multi-card graphics setups. But that's not the case here, as both Kaby Lake chips have the same 16 lanes as Intel's mainstream Core i5 and Core i7 chips. If you want to plug in all the drives and cards you can, you'll have to opt for a Skylake X chip. That might be a smart idea regardless, because the next chip up the Core X stack, the Core i7-7800X, costs just $50 more ($389) and delivers 28 lanes of PCIe, plus two extra cores.

Image: Intel Core X (Two in Boxes).jpg

That leaves us with one primary reason for the Core i7-7740X's existence from a consumer standpoint: If you're building a system that you intend to turn into a powerhouse machine loaded up with high-end storage and hardware down the line, but you don't have lots of money today to drop on an extremely expensive CPU. The Core i7-7740X will let you add a high-end graphics card and a speedy storage drive or three, while giving you an upgrade path for something more powerful once your budget allows.

But even then, if you just want to jump into the platform, the four-core Core i5-7640X will get you there for less (under $250), with the primary sacrifice being thread-doubling Hyper-Threading support. And if you can make use of those extra threads, the six-core Core i7-7800X again delivers four more threads than the Core i7-7740X, plus 75 percent more PCIe lanes (28 versus 16) for just $50 more.

Sometimes, being in the middle of a product stack means you get the best balance of price, performance, and features. Other times, getting stuck in the middle means a long backseat car ride sitting on the uncomfortable hump, flanked by passengers on either side that seem to have more interesting lives than you do. We're not saying things are quite as bad as the latter scenario for the Core i7-7740X. But if we were outfitting a new X299 system today, whether it be a modest gaming rig or an all-out enthusiast media-creation powerhouse, we'd focus our attention on one of the other options in the Core X lineup that either costs less, or offers more useful features for a little extra cash.

Intel Core i7-7740X



  • High base clock speed.


  • Only 16 PCI Express lanes on the CPU.

The Bottom Line


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