Intel Core i7-7740X review: One fast but awkward processor

A mainstream processor on an enthusiast platform

The AMD Ryzen Threadripper 1950X is a 16-core/32-thread CPU. Intel’s got an 18-core/36-thread chip coming at the end of September.

With both AMD and Intel cramming cores into their chips with such impunity, it’s easy to get carried away in the heady tailwinds of the time. More cores! Progress! Technology is great.

However, this year was also the year that Intel introduced quad-core processors in its HEDT (high-end desktop) line-up. These are the Kaby Lake-X class Core i5-7640X (4.0GHz, 6MB L3 cache) and Core i7-7740X (4.3GHz, 8MB L3 cache) processors that cost US$242 and US$339 respectively, the same as their respective Kaby Lake counterparts.

This was interesting for many reasons, but it was also puzzling. Intel’s HEDT processors have traditionally utilized architectures that trailed the mainstream parts by a generation, but these Kaby Lake-X chips featured the latest silicon. Furthermore, it meant that you could get a Kaby Lake-X processor with an Intel X299 motherboard – saving a lot in the process – and upgrade to a Core i9 chip later if you wanted.

Unfortunately, it also meant a lot more confusion. The Core i7-7740X only nets you 16 PCIe 3.0 lanes from the CPU, and supports just dual-channel DDR4 memory. Now consider that the X299 platform was designed for up to 44 PCIe 3.0 lanes and quad-channel memory configurations.

The result is you end up with a lot of supported features that simply aren’t available with the Core i7-7740X. These gaps are glaring – on a motherboard with eight slots for memory modules, only four will work with the latter CPU.

Furthermore, Intel’s Core X family comprises CPUs with 16, 28, and 44 PCIe lanes, and motherboard makers need to ensure that their X299 boards work with all three configurations. They add PCIe switches to manage this and route the lanes for different CPUs, which adds to the final cost of each board.

On top of that, there’s the issue of differing power delivery designs. Skylake-X uses an integrated voltage regulator, a partial holdover from the fully-integrated voltage regulator (FIVR) on Broadwell, so the processor isn’t entirely reliant on the motherboard for voltage delivery.

The problem is that Kaby Lake-X doesn’t use an integrated voltage regulator. All its voltages are supplied by the motherboard, and this complicates matters because board makers now have to support both types of power delivery. The motherboard will also have to check at boot to see what type of CPU it has to ensure that it serves up the correct voltages, which can lead to longer boot times.

To be fair, there are now boards designed specifically for Kaby Lake-X (they won’t work with Skylake-X), so it’s possible to get something more optimized for the Core i7-7740X. But this only seals off your future upgrade path, and it leaves the Core i7-7740X with little to distinguish itself from the Core i7-7700K and an Intel Z270 board.

A tweaked Core i7-7700K

The Core i7-7740X can be thought of as a Core i7-7700K with modest changes (other than the larger package size of course). Clock speeds have been bumped up to 4.3GHz, a 100MHz increase, but Turbo Boost speeds and cache sizes are unchanged. However, memory support has been extended to include up to DDR4-2666, compared to DDR4-2400 on the Kaby Lake part.

The TDP now sits at 112W, up from 91W on the Core i7-7700K. This unfortunately isn’t a product of some under-the-hood boost in processing power, and the underlying architecture is still the same as its Kaby Lake sibling. This means the chip also doesn't benefit from the new Turbo Boost Max Technology 3.0 or the rejigged cache hierarchies on Skylake-X.

That said, Intel also chose to disable the HD Graphics 630 iGPU that’s still physically present on the chip. This effectively gets rid of many features that could appeal to mainstream consumers, such as native HEVC encode and decode. You could argue that enthusiasts wouldn’t miss these features, but it’s also a bit of a stretch for a so-called enthusiast to settle for a quad-core processor.

Ultimately, you’re left to contend with a confusing processor that appears a tad misguided. Intel’s lowering the barrier to entry to its HEDT line-up, but it’s not quite clear who it’s appealing to here.

Nevertheless, it’d be overly hasty to simply dismiss the Core i7-7740X without putting it through the paces. This is still Intel’s highest clocked processor at 4.3GHz, and there’s considerable overclocking headroom to be had for those who must have blistering single-threaded performance.

Test Setup

The configurations of the test setups we used for the different processors are listed below. However, the CPU cooler used differed between systems due to compatibility issues across the different sockets.

Intel Core X

• Intel Core i9-7900X (3.3GHz, 13.75MB L3 cache) / Intel Core i7-7740X (4.3GHz, 8MB L3 cache)
• Cooler Master MasterLiquid 240
• Gigabyte X299 Aorus Gaming 9
• 4 x 4GB Corsair Vengeance LPX DDR4-2666 (Auto timings: CAS 15-17-17-35)
• NVIDIA GeForce GTX 1080 Ti (GeForce Driver Version 384.94)
• Samsung 850 EVO 250GB SSD
• Windows 10 Home (64-bit)

AMD Ryzen Threadripper

• AMD Ryzen Threadripper 1920X (3.5GHz, 32MB L3 cache)
• Thermaltake Floe Riing 360 TT Premium Edition
• ASUS ROG Zenith Extreme
• 4 x 4GB Corsair Vengeance LPX DDR4-2666 (Auto timings: CAS 15-17-17-35)
• NVIDIA GeForce GTX 1080 Ti (GeForce Driver Version 384.94)
• Samsung 850 EVO 250GB SSD
• Windows 10 Home (64-bit)

Intel Kaby Lake

• Intel Core i7-7700K (4.20GHz, 8MB L3 cache)
• Cooler Master MasterLiquid 240
• ASUS ROG Maximus IX Formula
• 4 x 4GB Corsair Vengeance LPX DDR4-2666 (Auto timings: CAS 15-17-17-35)
• NVIDIA GeForce GTX 1080 Ti (GeForce Driver Version 384.94)
• Samsung 850 EVO 250GB SSD
• Windows 10 Home (64-bit)

AMD Ryzen

• AMD Ryzen 7 1800X (3.60GHz, 16MB L3 cache)
• Noctua NH-U12S SE-AM4
• Gigabyte Aorus AX370 Gaming 5
• 2 x 8GB Corsair Vengeance LPX DDR4-3000 at 2,666MHz (Auto timings: CAS 16-16-16-36)
• NVIDIA GeForce GTX 1080 Ti (GeForce Driver Version 384.94)
• Samsung 850 EVO 250GB SSD
• Windows 10 Home (64-bit)

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Next, here’s a list of the benchmarks used:

• SYSmark 2014 SE
• PCMark 10
• SPECviewperf 12.1
• Cinebench R15
• Handbrake 1.0.7
• 3DMark (2013)
• Ashes of the Singularity: Escalation
• Deus Ex: Mankind Divided

Performance results

SYSmark 2014 SE

SYSmark is a general productivity benchmark suite that measures the response times of tasks on a PC using real-world applications like Microsoft Office 2013 and Adobe Photoshop and simulated user input. Task response times are used to generate a performance rating that reflects actual user experience, so the faster a PC responds to application workloads, the higher its score will be. The method of measuring response times can take many forms, such as the time it takes for an application to show a pop-up completion message, or how long it takes a progress dialog to disappear and for a user to regain application control.

The 2014 SE version of SYSmark adds a new Responsiveness usage model, where the system's ability to react quickly to user input affects the overall user experience. This means situations where the system needs to respond smoothly and quickly, such as with application launches, multi-tab web browsing, file copying, and background app installation.

The Intel Core i7-7740X did quite well here, second only to the Core i9-7900X in terms of overall score. However, it’s important to note that the Core i7-7700K, technically a mainstream chip, performed the same for all practical intents and purposes.

The workload breakdown reveals more about the performance characteristics of the chip, where it predictably fell behind the processors with more cores and threads in media creation and data/financial analysis-type tasks.

However, the high single-core clocks of the Core i7-7740X and Core i7-7700K helped them come ahead in less heavily threaded workloads like office productivity and measures of responsiveness.

PCMark 10 Extended

PCMark 10 Extended assesses the performance of systems in a variety of workloads, including basic computing tasks, productivity applications, digital content creation, and gaming. Compared to PCMark 8, it also adds in new test metrics, such as app startup times, which quantifies how long it takes to launch a variety of real-world apps, and a rendering and visualization workload to simulate professional graphics and engineering applications. In addition, existing workloads have been updated to reflect modern usage

We’ve also added in a graph to reflect the low-level breakdown of scores to give an idea of performance in individual workloads.

The Core i7-7740X was again second to only the Core i9-7900X, but this time it beat the Core i7-7700K by nearly 7 per cent. As in SYSmark 2014 SE, the Kaby Lake-X processor had a strong performance in basic computing and productivity tasks such as web browsing, spreadsheets, and work productivity.

On the other hand, more cores helped the Core i9 chip edge ahead in things like photo editing and rendering and visualization.

SPECviewperf 12.1

SPECviewperf is used to assess the 3D graphics performance of systems in professional applications. Each individual workload, called a viewset, represents graphics and content from an actual real-world application. SPECviewperf actually runs a total of eight different viewsets, but we’ve picked the four which have the greatest performance variation across CPUs display here.

The 3ds-max viewset comes from traces of the graphics workload generated by 3ds Max 2016, while maya-04 is derived from Autodesk’s Maya 2013 application. The catia-04 viewset involves the numerous rendering modes from the CATIA V6 R2012 application, and includes things like anti-aliasing, depth of field, and ambient occlusion. Finally, the sw-03 viewset comes from SolidWorks 2013 SP1, and involves various rendering modes including environment maps.

Both the Core i7-7740X and Core i7-7700K were pretty much on par here, although the latter did take a small lead in the 3ds-max viewset. Having said that, SPECviewperf 12.1 clearly doesn’t scale very well with high thread counts, and the two quad-core chips outstripped everything else.

Cinebench R15

Cinebench R15 is a better indicator of Threadripper and the Core i9’s performance because of its ability to utilize up to 256 threads to evaluate a processor’s performance in a photorealistic 3D rendering. We ran both single-core and multi-core benchmarks to evaluate single-threaded performance and multi-threaded scalability here.

Unsurprisingly, the higher-end HEDT processors had the clear advantage here, and the Core i7-7740X and Core i7-7700K trailed even the Ryzen 7 1800X by a good 38 per cent in the multi-threaded benchmark. The Core i7-7740X was also behind the 10-core Core i9-7900X by a whopping 54 per cent.

The quad-core CPUs redeemed themselves in the single-threaded scenario, where they achieved parity with the Core i9-7900X. The latter has a Turbo Boost Max 3.0 speed of 4.5GHz, which is why it managed to keep up with the higher clocked quad-core processors.

Either way, it’s apparent that the Core i7-7740X excels in tasks which prioritize high IPC, and the same goes for the Core i7-7700K as well.

Handbrake 1.0.7

Handbrake is a video transcoder that converts videos into a format for use on PCs and portable electronic devices, and is a good indicator of a processor’s video encoding capabilities. YouTube content creators, Twitch streamers, and other video creators will be most interested in this performance metric.

The Core i7-7740X and Core i7-7700K were at a distinct disadvantage here, as video encoding is one of the tasks that can benefit hugely from having more cores and threads. Both processors took more than double the time of the Core i9-7900X, so they’re not quite the best chips for hardcore streamers.

Temperature and power consumption

To test temperature and power consumption, we ran the 3DMark Fire Strike Extreme Stress test and the energy-01 viewset in SPECviewperf 12.1 respectively, taking note of the peak values the chips achieved. For power consumption, this refers to the total system power draw from the power outlet.

It’s difficult to compare temperatures across all the chips given that we used different coolers, so these figures are better taken as a rough indicator to the temperatures you can expect in a typical gaming scenario (which probably doesn’t stress all the cores anyway).

The Core i7-7740X guzzled more power than the Core i7-7700K, and was roughly on par with the total system power draw of the Core i9-7900X. Temperature-wise, it ran fairly cool with our AIO liquid cooler, although it was still marginally hotter than the Kaby Lake chip.

Gaming benchmarks and overclocking

3DMark (2013)

The synthetic 3DMark benchmark tests graphics and computational performance at different resolutions, starting at 1080p and going all the way up to 4K. A series of two graphics test, one physics test, and then a combined test stresses your hardware in turn to assess its performance. And because of the physics test that keeps the GPU load low while running gameplay physics simulations on the CPU, all three 3DMark Fire Strike tests scores also include an element of CPU performance.

We’ve also teased out the Physics and CPU scores for the Fire Strike and Time Spy tests and compiled them in separate tables to give a better idea of how each processor performed.

There actually isn’t a lot that separates the quad-core processors from something like the 10- and 12-core Intel Core i9-7900X and Ryzen Threadripper 1920X in terms of gaming performance. For instance, the Core i7-7740X trailed the Core i9-7900X by only two per cent in 3DMark Fire Strike.

The performance difference becomes a bit more pronounced in the more CPU-intensive Time Spy benchmark, where the gap between the latter two chips widened to roughly 13 per cent.

The breakdown of the Physics and CPU scores reflects this more clearly, with the two quad-core chips trailing the others by a significant amount. In fact, the Core i9-7900X was a good 75 per cent quicker than the Core i7-7740X when looking at the Time Spy CPU scores.

Ashes of the Singularity: Escalation

Ashes of the Singularity: Escalation was one of the first games to be updated with optimizations for Ryzen, and both Threadripper processors come very close to challenging the Intel Core i9-7900X in DirectX 12 mode at 1080p.

Ashes of the Singularity is one of the few CPU-bound games out there, if you’re playing on lower resolutions and settings that is.

This is also a title that has reportedly been tweaked to better take advantage of multiple cores, so it’s not surprising to see the Core i9-7900X and Ryzen Threadripper 1920X edge ahead here, especially at the less demanding settings (the 1920X's lead is mostly limited to DirectX 12 mode).

The performance differential narrows as we move to more demanding GPU-bound scenarios, so the resolution you intend to game at may play some role in your decision on which chip to get.

Deus Ex: Mankind Divided

Deus Ex: Mankind Divided is one of the most taxing games out there, and differences in CPU performance don’t matter all that much here.

Both the Core i7-7740X and Core i7-7700K were mostly neck-and-neck with the Core i9-7900X, and moving to a 4K resolution clearly creates a highly GPU-bound scenario where all the tested chips performed nearly identically to each other.

It’s also to the credit of the Core i7-7740X that it manages to outperform last generation’s deca-core flagship, the Core i7-6950X, in the 1080p benchmarks.

Overclocking

This table below summarizes the clock speeds, the voltages we used to achieve them, and the respective performance gains.

The Core i7-7740X proved to be quite an excellent overclocker, not unlike the Core i7-7700K. We managed to hit a top speed of 5.08MHz, slightly higher than the latter Kaby Lake processor. This translated into around an 11 per cent boost in Cinebench’s multi-threaded benchmark, and a similar 11 per cent uptick in the single-threaded score.

It’s safe to say that Kaby Lake-X overclocks far better than its higher-end Skylake-X counterparts, and it stands to reason that you could push it a lot further with a high-end custom liquid cooling loop.

So is this supposed to be an HEDT or mainstream chip?

Intel had a nice idea with Kaby Lake-X. Adapt a mainstream chip for the Core X HEDT family, and make it the same price as the Core i7-7700K! It’ll work with an Intel X299 motherboard, so you can save now, and easily upgrade to a higher end Core i9 chip later.

This sounds great on paper. Suddenly, a lot more consumers are going to be able to access Intel’s enthusiast class platform, which may tempt them to get higher value processors further down the road.

However, it’s not that simple to execute, and Intel’s segmentation of features across the entire Core X line-up creates a lot of confusion and limitations. Yes, the Core i7-7740X will work with Intel X299, but it only comes with 16 PCIe 3.0 lanes, so chances are there will be features you paid for on your motherboard that simply aren’t going to work.

X299 boards are also more costly, so you might end up in a situation where the price of the board simply feels disproportionate to the price of the CPU.

For example, the ASUS TUF X299 Mark 2 costs S$459 here, and that’s already one of the cheaper X299 boards available now. If you get it in a bundle with the Core i7-7740X, it’ll cost you around S$918.

On the other hand, the TUF Z270 Mark 2 is over a hundred dollars cheaper at S$309. Together with the Core i7-7700K, it costs S$766. That’s a S$152 price premium for barely any tangible gain.

Similarly, the ASUS ROG Strix X299-E Gaming retails for S$1,058 with the Core i7-7740X, while the equivalent Z270 board, the ROG Strix Z270E Gaming, is asking for S$846 with the Core i7-7700K. This time, that’s a S$212 difference in price.

Furthermore, the Core i7-7740X is for all practical intents and purposes the same chip as the Core i7-7700K. There are barely any significant differences in performance between the two, and pairing the former with an X299 motherboard nets you exactly zero new features over Intel Z270.

Sure, the Core i7-7740X overclocks a bit better, but that’s hardly worth the additional cost unless you're on a one-track mind to achieve new overclocking feats.

The Core i7-7700K is an excellent gaming chip, so what Intel has done is basically transplant that chip onto its HEDT platform with a few tweaks, and made it such that you’ll have to pay for a more expensive motherboard and not use all the features.

There are a few saving graces. For instance, manufacturers have begun making motherboards specific to Kaby Lake-X, so these will likely be cheaper. Unfortunately, this also defeats the purpose of buying Kaby Lake-X with X299 in the first place – the freedom to upgrade in the future.

The Core i7-7740X is a fast and powerful chip, make no mistake. But given that we already have the Core i7-7700K, it puts the Kaby Lake-X processor in a bit of a pickle. Why does it even need to exist?

It seems to be going after consumers who are attracted by the appeal of the HEDT X299 platform, but are unwilling to shell out over S$1,800 for an X299 board and Core i9-7900X. Unfortunately, these undecided folks probably don’t number that many, and it simply makes more sense to make up your mind before buying.

If you’re just a regular gamer, the Core i7-7700K is the more sound choice. You get to enjoy the maturity of the Z270 platform, save about a couple hundred dollars, and still get one of the best gaming CPUs out there. Similarly, enthusiasts, professional content creators, or anyone else working with heavily threaded workloads would likely go straight for the Skylake-X processors or even AMD’s Ryzen Threadripper.

The Core i7-7740X fills an uncertain niche, and it’s bogged down by the limitations it imposes on the X299 platform. That’s a pity really, as this is a great CPU that looks like it simply cannot decide on its purpose.

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