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The Core i7-7740X is one of the new CPUs from Intel using socket LGA2066. With four cores, eight threads and maximum clock of 4.5 GHz, it is aimed on the top/mainstream segment. Check it out!
Recently, Intel launched a new high-end platform, the X299, that uses the new LGA2066 socket. The new CPUs for this platform are codenamed Kaby Lake-X and Skylake-X, and while the highest-end model is the Core i9-7900X (read its review here), which has 10 physical cores, 20 threads, 3.3 GHz base clock, and 4.5 GHz Turbo clock, the Core i7-7740X has only four cores, among other limitations.
The X299 platform comes to replace the previous HEDT (high-end desktop) platform, X99. The main feature of this platform is, besides the support for high-end CPUs, the memory access in four channels.
For this platform, Intel launched not only high-end CPUs, with six or more cores, but also two four-core CPUs, the Core i7-7740X (which we are reviewing today) and one Core i5. These two processors are based on the “Kaby Lake X” architecture, while the other ones are based on “Skylake-X” architecture. Besides having less cores, these two basic moldels have only 16 PCI Express 3.0 lanes, and access memory with only two channels.
The table below shows the CPUs launched (so far) for this new platform. Intel already annouced a few more models to be launched briefly.

Model Base Clock Turbo Boost Clock Cores/Threads L3 Cache PCI Express lanes TDP Memory channels MSRP
Core i9-7900X 3.3 GHz 4.3 GHz 10/20 13.75 MiB 44 140 W 4 USD 999
Core i7-7820X 3.6 GHz 4.3 GHz 8/16 11 MiB 28 140 W 4 USD 599
Core i7-7800X 3.5 GHz 4.0 GHz 6/12 8.25 MiB 28 140 W 4 USD 389
Core i7-7740X 4.3 GHz 4.5 GHz 4/8 8 MiB 16 112 W 2 USD 339
Core i5-7640X 4.0 GHz 4.2 GHz 4/4 8 MiB 16 112 W 2 USD 242

As you can see, the Core i7-7740X does not offer two of this platform highlights: the quad-channel memory access, and the high number of PCI Express lanes. Actually, its specs are very similar to the Core i7-7700K’s, except for 100 MHz more on the base clock and the official support to DDR4-2666 memories. Besides that, it is basically the same CPU packed on a new socket, even costing the same.
On some motherboards, there is not even support for a PCI Express 3.0 x16 slot when a Kaby Lake-X CPU is being used; even a single video card will work at x8 speed. Besides that, with these processors, you can only use half of the motherboard sockets, because the memory controlled embedded in the CPU supports only two channels, not four.
Figure 1 shows the Core i7-7740X CPU.

Core i7-7740XFigure 1: the Core i7-7740X

In Figure 2 we have the underside of the CPU.

Core i7-7740XFigure 2: underside of the Core i7-7740X

Figure 3 shows the Core i7-7740X at the side of the Core i9-7900X. Notice that they use the same socket, but have different heatspreaders.

Core i7-7740XFigure 3: the Core i7-7740X (left) and the Core i9-7900X (right)

For our benchmarks, we compared the Core i7-7740X to the the Ryzen 7 1700X (read review here), which is its direct competitor. We also included the Core i7-7700K (review), which is very similar to the reviewed CPU. We also included the Core i9-7900X (read the review) and the Core i7-6950X (review here), but please mind that those two last ones are not direct competitors to the Core i7-7740X, because they cost a lot more.
We used a GeForce GTX 1080 video card on all tests.
Let’s compare the main specs of the reviewed CPUs in the next page.
[nextpage title=”The Reviewed CPUs”]
In the tables below, we compare the main features of the CPUs included in our review.

CPU Cores HT/SMT IGP Internal Clock Turbo Clock Core Tech. TDP Socket Price
Core i7-7740X 4 Yes No 4.3 GHz 4.5 GHz Kaby Lake-X 14 nm 112 W LGA2066 USD 350
Ryzen 7 1700X 8 Yes No 3.4 GHz 3.8 GHz Sumit Ridge 14 nm 95 W AM4 USD 340
Core i7-7700X 4 Yes Yes 4.2 GHz 4.5 GHz Kaby Lake 14 nm 91 W LGA1151 USD 340
Core i9-7900X 10 Yes No 3.3 GHz 4.3 GHz Skylake-X 14 nm 140 W LGA2066 USD 1050
Core i7-6950X 10 Yes No 3.0 GHz 3.5 GHz Broadwell-E 14 nm 140 W LGA2011-v3 USD 1650

Below you can see the memory configuration for each CPU.

CPU L2 Cache L3 Cache Memory Support Memory Channels
Core i7-7740X 4 x 256 kiB 8 MiB Up to DDR4-2667 2
Ryzen 7 1700X 8 x 512 kiB 2 x 8 MiB Up to DDR4-2667 2
Core i7-7700K 4 x 256 kiB 8 MiB Up to DDR4-2400 2
Core i9-7900X 10 x 1 MiB 13.75 MiB Até DDR4-2667 4
Core i7-6950X 10 x 256 kiB 25 MiB Até DDR4-2400 4

[nextpage title=”How We Tested”]During our benchmarking sessions, we used the configuration listed below. Between our benchmarking sessions, the only variable devicand was the CPU being tested, besides the motherboard, which had to be replaced to match the different CPUs.
Hardware Configuration

Operating System Configuration

  • Windows 10 Home 64-bit
  • NTFS
  • Video resolution: 1920 x 1080 60 Hz

Driver Versions

  • NVIDIA driver version: 384.94

Software Used

Error Margin
We adopted a 3% error margin. Thus, differences below 3% cannot be considered relevant. In other words, products with a performance difference below 3% should be considered as having similar performance.
[nextpage title=”PCMark 10 and 3DMark”]

PCMark 10

PCMark 10 is a benchmarking software that uses real-world applications to measure the computer performance. We ran the “Extended” test, which included applications opening, web browsing, writing, gaming, photo editing, video chat, video conversion, and rendering. Let’s see the results.
Core i7-7740X
On the 3DMark 10 Extended benchmark, the Core i7-7740X was 19% faster than the Ryzen 7 1700X, and performed similarly to the Core i7-7700K.

3DMark

3DMark is a program with a set of several 3D benchmarks. Time Spy runs a DirecX12 simulation; Fire Strike runs a “heavy” DirectX 11 simulation, and Sky Diver also measures DirectX 11 performance, but is aimed on average computers.

Core i7-7740X

On Time Spy, the Core i7-7740X was on a technical tie to the Ryzen 7 1700X and to the Core i7-7700K.

Core i7-7740X

On the Fire Strike benchmark, the Core i7-7740X was 16% faster than the Ryzen 7 1700X, and performed similarly to the Core i7-7700K.

Core i7-7740X

On the Sky Diver benchmark, the Core i7-7740X was 7% slower than the Ryzen 7 1700X, and performed similarly to the Core i7-7700K.

[nextpage title=”Performance in programs”]

Cinebench R15

Cinebench R15 is based on the Cinema 4D software. It is very useful to measure the performance gain obtained by the presence of several processing cores while rendering heavy 3D images. Rendering is an area where a bigger number of cores helps a lot, because usually this kind of software recognize several processors (Cinebench R15, for example, can use up to 256 processing cores).
We ran the CPU benchmark, which renders a complex image using all the processing cores (real and virtual) to speed up the process. The result is given as a score.
Core i7-7740X
On Cinebench R15 CPU benchmark, the Core i7-7740X was 37% slower than the Ryzen 7 1700X, and performed similarly to the Core i7-7700K.

Blender

Blender is a image and movie redering software that uses all the threads of the CPU. We used the program to render a heavy image of a project named Gooseberry Benchmark. The graph below shows the time the CPU used to finish the image, so the less, the better.
Core i7-7740X
On Blender, the Core i7-7740X was 26% slower than the Ryzen 7 1700X, and performed similarly to the Core i7-7700K.

CPU-Z

On its current version, the well-known hardware identification software CPU-Z comes with a benchmarking tool, which measures CPU performance for one core and for all available cores.
Core i7-7740X
On the single thread benchmark, the Core i7-7740X was 25% faster than the Ryzen 7 1700X, and performed similarly to the Core i7-7700K.
Core i7-7740X
On the multiple thread benchmark, the Core i7-7740X was 38% slower than the Ryzen 7 1700X, and again performed like the Core i7-7700K.

Handbrake

Media Espresso is a video conversion program that uses the graphics processing unit of the video engine to speed up the conversion process. We converted a 1 GiB, 1920x1080i, 23,738 kbps, .mov video file to a smaller 320×200, H.264, .MP4 file for viewing on a smartphone. The results below are given in seconds, so the lower the better.

Core i7-7740X

Here the Core i7-7740X was 32% slower than the Ryzen 7 1700X, and obtained the same performance of the Core i7-7700K.

WinRAR

Another task where the CPU is very demanded is on file compacting. We ran a test compacting a folder with 8 GiB on 6.813 files to a file, using WinRAR 4.2. The graph below shows the time taken on each test.
Core i7-7740X
On WinRAR, the Core i7-7740X was similar to the Ryzen 7 1700X, and was 6% slower than the Core i7-7700K.
[nextpage title=”Gaming Performance”]

Deus Ex: Mankind Divided

Deus Ex: Mankind Divided is an action RPG with FPS elements, launched in August 2016, that uses the Dawn engine, being compatible with DirectX 12. We tested it using the benchmark included in the game, with DirectX 12 enabled, Full HD, and graphic options as “high”.
The results below are expressed in frames per second.
Core i7-7740X
On this game, the Core i7-7740X was 9% faster than the Ryzen 7 1700X, and performed similarly to the Core i7-7700K.

Grand Theft Auto V

Grand Theft Auto V, or simply GTA V, is an open-world action game released for PCs in April of 2015, using the RAGE engine. In order to measure the performance on this game, we ran the performance test of the game, measuring the framerate with FRAPS. We ran GTA V at Full HD, with all image quality set as “high” and MSAA off.

The results below are expressed in frames per second.

Core i7-7740X

On GTA V, the Core i7-7740X was 16% faster than the Ryzen 7 1700X, and performed similarly to the Core i7-7700K.

Hitman

Hitman is an action/stealth game, launched in March 2016, that uses a DirectX 12 compatible version of the Glacier 2 engine. To measure performance in this game, we ran the benchmark in it, measuring the framerate with FRAPS. We ran this game with DirectX 12 enabled, with image quality set as “high”.
The results below, in Full HD and 4K, are expressed in frames per second.
Core i7-7740X
On Hitman, the Core i7-7740X was 16% faster than the Ryzen 7 1700X, and 6% slowe than the Core i7-7700K.

Rise of the Tomb Rider

Rise of the Tomb Rider is an adventure/action game launched in January of 2016, based on Foundation engine. In order to measure the performance using this game, we ran the benchmark included on it, using Full HD resolution and graphics quality set to “medium”.
The results below are expressed in frames per second.
Core i7-7740X
Also on Rise of the Tomb Rider, the Core i7-7740X was 11% faster than the Ryzen 7 1700X, and performed similarly to the Core i7-7700K.

Tom Clancy’s Rainbow Six Siege

Tom Clancy’s Rainbow Six Siege is a tactical FPS game launched in December of 2015, based on AnvilNext engine. In order to measure the performance using this game, we ran the benchmark included on it, using Full HD resolution and graphics quality set to “high”.
The results below are expressed in frames per second.
Core i7-7740X

On this game, the Core i7-7740X was 5% faster than the Ryzen 7 1700X, and performed similarly to the Core i7-7700K.

[nextpage title=”Overclocking”]
All the LGA2066 processors have unlocked clock multiplier, which means you can overclocking it just by changing its multiplier, as long as the motherboard has this feature.
We were able to configure the CPU to run stable at 4.9 GHz (100 MHz reference clock and x49 multiplier), with the original voltages. Raising Vcore to 1.3 V, we were able to run it stable at 5.0 GHz, which is a great mark. It may be possible to reach higher frequencies if you “play” with the available adjusts, as long as you have a good power supply, motherboard, and cooling system.
It is also good to keep in mind that the overclock capability depends on pure luck, since two CPUs of same model can reach different maximum clocks.
[nextpage title=”Conclusions”]
Some things were clear on our tests. First, the Core i7-7740X has practically the same performance of the Core i7-7700K, what was predictable since they are very similar on most specs. Only in games we noticed a slightly smaller performance of the Core i7-7740X, which is possibly due to the fact that, on the motherboard we used, the video card works at x8 speed with this processor.
It is also clear that, just like the Core i7-7700K, the Core i7-7740X is faster than the Ryzen 7 1700X on games, but slower on tasks that use all available cores, like Cinebench, Blender, and Handbrake. We actually can say the Core i7-7740X and the Core i7-7700K are today’s CPUs with the best single-thread performance.
But what was not clear for us is what is the market Intel intends to hit with this new CPU. Socket LGA2066 mainboards are way more expensive than the LGA1151 ones, mostly because of features that the Core i7-7740X will not use, like four memory channels and the several PCI Express 3.0 x16 slots. So, a computer based on the Core i7-7700K will cost less, even if both CPUs costs the same (and it will perform the same way).
It should be an interesting CPU for high-end gaming computers if it wasn’t the limitation of 16 PCI Express lanes (the Core i7-7700K has 24 lanes, for example), which makes it a bad choice if you intend to use two or more video cards.
One of the situations the Core i7-7740X could be used is if you want to build a computer using the HEDT LGA2066 platform now with a mainstream CPU, changing for a high-end processor in the future, but is doesn’t make much sense because you will have to spend two times.
Other situation is for overclocking enthusiast: the Core i7-7740X has a great overclocking potential, better than the Core i7-7700K, because it uses a more robust platform, designed for higher consumption CPUs.
Because all of this, even being one of the fastests CPUs for gaming available today on the market, the fact it uses an expensive platform gives it a bad cost/benefit ratio.