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Appeared on: Friday, October 6, 2017
Intel Core i7-8700K and Core i5-8400 benchmarks

1. Meet the Intel Core i7-8700K and Core i5-8400 CPUs

We were looking forward for Intel's first six-core parts for the mainstream PC market. But now the company is finally launching the Intel's new 8th Generation Coffee Lake CPUs, with the Core i5 and Core i7 parts having six distinct physical cores. Today we are running some benchmarks with the top SKU, the Core i7-8700K, along with looking at numbers from the Core i5-8400, comparing them with the Core i7-7700K and the AMD Ryzen 7 1700 parts.

Intal is actually releasing six desktop processors that all fall under the '8th Generation' nomenclature, and are built under the codename 'Coffee Lake' to designate the microarchitecture and manufacturing process combination.

All these new processors require appropriate motherboards featuring the Z370 chipset. Technically these processors use the LGA1151 socket, which is also used by the 6th Generation and 7th Generation processors with the Z170 and Z270 chipsets. However due to differences in the pin-layout of these two sets of processors, 8th Gen will only work in Z370 boards and there is no level of cross compatibility.

Intel 8th Generation 'Coffee Lake' Desktop Processors
  i7-8700K i7-8700 i5-8600K i5-8400 i3-8350K i3-8100
Cores 6C / 12T 6C / 6T 4C / 4T
Base Frequency 3.7 GHz 3.2 GHz 3.6 GHz 2.8 GHz 4.0 GHz 3.6 GHz
Turbo Boost 2.0 4.7 GHz 4.6 GHz 4.3 GHz 4.0 GHz - -
L3 Cache 12 MB 9 MB 8 MB 6 MB
DRAM Support DDR4-2666 DDR4-2400
Integrated Graphics Intel UHD Graphics 630 GT2: 24 EUs Intel UHD Graphics 630 GT2: 23 EUs
IGP Base Freq 350 MHz 350 MHz
IGP Turbo 1.20 GHz 1.15 GHz 1.05 GHz 1.15 GHz 1.10 GHz
PCIe Lanes (CPU) 16 16
PCIe Lanes (Z370) < 24 < 24
TDP 95 W 65 W 95 W 65 W 91 W 65 W
Price (tray) $359 $303 $257 $182 $168 $117

The Core i7-8700K starts at a 3.7 GHz base frequency and is designed to turbo to 4.7 GHz in single threaded workloads, with a thermal design power (TDP) of 95W. The K designation means this processor is unlocked and can be overclocked by adjusting the frequency multiplier, subject to appropriate cooling, applied voltage, and the quality of the chip (Intel guarantees 4.7 GHz). The Core i7-8700 is the non-K variant, with lower clocks (3.2 GHz base, 4.6 GHz turbo) and a lower TDP (65W). Both of these processors use 256 KB of L2 cache per core and 2 MB of L3 cache per core.

Intel‚??s newest '14++' manufacturing process is being used for these 8th Generation processors. Intel has decided that it will use multiple process nodes and microarchitectures across a single generation of products. A lot of this is down to product maturity, yields, and progress on the manufacturing side.

With a new processor generation comes an update to memory support. Intel is supporting DDR4-2666 for the six-core parts and DDR4-2400 for the quad-core parts, in both 1DPC (one DIMM per channel) and 2DPC modes.

Intel has made it clear that Coffee Lake processors will work only in Z370 motherboards, and not in the previous generation Z270 motherboards.

All the six processors being made available today will have Intel‚??s UHD Graphics 630. This is basically identical to the previous generation's HD Graphics 630, except the name is now UHD. The other change is HDCP2.2 support.

Intel claims that there are performance improvements with the new graphics package, mainly from an updated driver stack but also increased frequencies. All the parts will have an idle frequency of 350 MHz, and boost up to the following frequencies:

  i7-8700K i7-8700 i5-8600K i5-8400 i3-8350K i3-8100
Integrated Graphics GT2: 24 EUs GT2: 23 EUs
IGP Base Freq 350 MHz 350 MHz
IGP Turbo 1.20 GHz 1.20 GHz 1.15 GHz 1.05 GHz 1.15 GHz 1.10 GHz

The Z370 chipset is identical to the Z270 chipset. The connectivity is the same, the number of supported PCIe 3.0 lanes is the same, the available bifurcation is the same, the controller support is the same. The chipset has 20-24 PCIe 3.0 lanes, six SATA 6 Gbps ports with support for RAID 0/1/5/10, a total of 14 USB ports (either 2.0 or 3.0, up to a maximum of ten of USB 3.0), and supports network controllers, Thunderbolt 3, and Intel‚??s Optane memory as a boot drive.

Looking at the prices and the compatition, the Core i7-8700K ($359) sits almost equally between the Ryzen 7 1700X ($399) and Ryzen 7 1700 ($329). Here this would be a battle of sixteen Zen threads compared to 12 Coffee Lake threads, with the IPC and frequency advantage on Intel‚??s side. It will be interesting to see where the Core i7-8700 ($303) sits in performance per dollar compared to the Ryzen 7 1700.

The Core i5-8600K ($257) costs almost the same as the Ryzen 5 1600X ($248). With Intel moving the Core i5 parts to having six full cores, albeit without hyperthreading but with a high frequency, it is going to be an interesting battle between the two at this price.

The Core i5-8400 ($182) and Core i3-8350K ($169) sit near the Ryzen 5 1500X ($189) and the Ryzen 5 1400 ($169) respectively.

For this review today, we are focusing on our preliminary testing of the Core i7-8700K and the Core i5-8400:

Here is out testbed:

CPU Core i7-8700K Core i5-8400 Core i7-7700K Ryzen 7 1700
Motherboard ASUS PRIME Z370-A (UEFI: 0408) ASUS PRIME Z270-A (UEFI: 1009) ASUS PRIME X370-PRO (UEFI: 0902)
Memory 16GB x 2 DDR4-2666
(2Ch, 19-19-19-43,1.20V)
16GB x 2 DDR4-2400
(2Ch, 17-17-17-39,1.20V)
16GB x 2 DDR4-2666
(2Ch, 19-19-19-43,1.20V)
GPU GeForce GTX 1080 8GB (Founders Edition)
Power supply KRPW-TI700W / 94 + (700W 80PLUS Titanium)
CPU Cooler Scythe Fuma SCFM-1000
Graphics driver GeForce Hotfix Driver version 385.69
OS Windows 10 Pro 64bit

2. Encoding - Cinebench R15, Handbrake, TMPG Video Mastering Works 6

We start our benchmarks with the Cinebench R15, as it gives an idea of single and multi-threaded thread performance. High frequency typicallgives performance in single-threaded tests, whereas having good scaling and many cores is where the multi-threaded test wins out.

The Core i7-8700K got the highest score in the chart, in both ST and MT tests, taking advantage of its high frequency, which peaked at the 4.7GHz. In the ST test the Core i7-8700K has an about 7% lead over the Core i7-7700K and also left the the Ryzen 7 1700 behind. With all cores working, AMD's chip closed the gap with the Core i7-8700K.

The Core i5-8400 chip hit the 4.0GHz blind and its reached about the 90% of the performance of the Core I7-7700K in the single core test. In addition, the Core i5-8400 has a lead over the Ryzen 7 1700 in ST.

Video transcoding is a hot topic in performance metrics as more and more content is being created. We tested the CPUs in H264 and HEVC (or H265) encoding using the Handbrake tool and TMPG Video Mastering Works 6 tools.

The Core i7-8700K is about 30-40% faster than the Ryzen 7 1700. In addition, the Core i5-8400 is also faster than Core i7-7700K by a smaller about 4%. Multi-thread performance is the game-changing factor in video encoding so even not the top Coffee Lake-S CPU is fsater than the top Kaby Lake-S CPU:


3. PCMark 10, Sandra Platinum

We use the PCMark 10 in order to get an idea of the overall performance of the PC.

The Core i7-8700K ranked first in the overall score. The Core i7-7700K ranked second, followed by the Core i5-8400 and the Ryzen 7 1700. Here the higher clock of the Core i7-7700K made the difference over the Core i5-8400.

We are moving on to the Sandra Platinum (24.43) benchmark suite.

The Core I7-8700K recorded the highest score among the CPUs in the chart in the Processor Arithmetic test. Intel's chip had a 15% lead over the AMD Ryzen 7 1700 in the integer arithmetic (Drystone) test, but this difference was narrowed down to about 3% in the floating point operations test (Whetstone).

The Core i5-8400 had a small (10%) lead over the Core i7-7700K in integer arithmetic test, and took a further 15-20% performance lead in the floating point arithmetic test.

In 'Processor Multi-Media' processing performance, the Core i7-8700K has a very clear lead over the rest CPUs. Also notice that the Core i7-7700K has a 35-60% performacne difference than the Ryzen 7 1700.

In the cryptographic performance test, the two Coffee Lake-S CPUs performed about 9% better than the Core i7-7700K. This should be attributed to the DDR4-2666 support of the new chips, over the DDR4-2400 memory supported by the Core i7-7700K.

The AMD Ryzen 7 1700 takes a significant lead over the Core i7-8700K (60%) in the hashing bandwidth test.

In the Memory Bandwidth test, both the Core i7-8700K and Ryzen 7 1700 CPUs supports DDR4-2666 and reached the31 GB/sec. The Core i5-8400 reached the 29.0 - 29.61 GB/sec, and the Core i7-7700K - which uses DDR4-2400 - is a bit slower.

4. 3D Mark Time Spy, Fire Strike Ultra and Fire Strike

The 3D Mark Time Spy becnhmark utilizes the DirectX 12.

The multi-thread performance of the CPUs are strongly reflected in their overall score here. The Core i7-8700K had highest overall score, with the Ryzen 7 1700 to follow. Notice that the 6-core, 6T Core i5-8400 CPU gave almost the same results with the quad-core, 8T Core i7-7700K:

In the Fire Strike Ultra and Fire Strike benchmarks, the small differences in the overall scores of the CPUs are mainly attributed to their respective 'Physics Score,' while the Graphics score of the chips in the Fire Strike Ultra is overall low.


5. VRMark Orange Room, Blue Room

We test the CPUs using the high FPS VRMark Orange Room and the demanding Blue Room tests. Obviously the Orange Room test is based on the single-threaded performance and adding more cores does not make any difference. On the other hand, in the demanding Orange Room test, the more cores available the better the performacn you get.


6. Gaming - Ashes of the Singularity: Escalation, Overwatch, The Witcher 3

Here we measure the systems' performances with the following games:

In the 'Ashes of the Singularity: Escalation' game we tested the CPUs using a resolution of 1,920 x 1,080 pixels in DirectX 12 mode and both the the "Standard" and "Crazy" quality settings.

The Core i7-8700K CPU gave some extra FPS during Standard DX12 gaming, but the performances in the Crazy DX12 test were almost the same for all the processors:

Again, all the processors gave similar results in terms of FPS in the 'Overwatch' and 'The Witcher 3' games:




7. Gaming - Ghost Recon Wildlands, Watch Dogs 2

We continue with the folliwng games::

Again all the Intel CPUs in this test behaved in a similar manner in the following games, and gave no significant gains in terms of FPS. The AMD Ryzen 7 1700 tests returned 4-7 less FPS than the Intel tests.


8. Power consumption, CPU temperature

Here we measured the power consumption of the entire PC system with each different CPU installed, during the VRMark, 3DMark, Cinebench R15 and TMPGEnc VMW6 tests.

Our goal was to give you an idea as to how much power each configuration used while idling at the Windows desktop and while under a heavy CPU workload. Keep in mind, this is total system power consumption being measured at the outlet with only the processor loaded and not the the individual power of the CPUs alone.

In an idle state, we measured a 35W power consumption for all the Coffee Lake-S CPUs. This value is lower than the 45W and the 37W we measured for the Ryzen 7 1700 and the older Core i7-7700K processors, respectively. But since we are measuring the total system power consumption of each system, this power difference could be attributed to the different motherboard we used for the AMD Ryzen 7 1700 test.

With all the CPU cores working in full load during the TMPGEnc Video Mastering Works 6 and the CINEBENCH R15 benchmarks, the system based on the Core i7-8700K CPU recorded 141~ 158W. The system that used the Core i5-8400 (TDP 65W) had the lowest power consumption in this comparison setup. Compared with the consumption of the Core i7-7700K, the Core i5-8400 consumed just 2~7 additional Watts:

We measured the CPU temperatures during various benchmarks using the HWMonitor.

The Core i7-8700K reached the 72 degrees C in during some benchmarks, close to the temperature of the Core i7-7700K. The Core i5-8400 was TDP 90W so it runs significantly cooler than the rest CPUs.



9. Final words

We finally have something bigger than a quad-core processor on Intel's mainstream platform. Although we have to do with new chips that are based on the same architecture as the processors preceded them, the addition of new cores is always welcome.

Both the Core i7-8700K and the Core i5-8400 processors have been designed offer more performance cores at more mainstream price points. After all, Intel is offering much more expensive chips for more complex platforms.

By moving from 4 cores / 8 threads to the 6 core / 12 threads, Intel Coffee Lake-S chips offer a 1.5 times improvement in the multi-threaded performance compared to the previous generation of Intel chips, at a reasonable cost. And compared with the AMD Ryzen chips, almost the same level of multi-threading gains at the same price range.

The Core i7-8700K mathed the multi-threaded performance of the Ryzen 7 1700, and also offered a little extra strength to the single-threaded performance level of a Core i7-7700K.

Nonetheless, in applications that need to take advantage of the extra cores, the Core i7-8700K will run through at an all-core turbo frequency of 4.3 GHz. The jump up from a quad-core to a hex-core for only a $20 difference cannot be neglected.

In addition, priced at $182 dollars, the Core i5-8400 offers you a performance that is seriously approaching the Core i7-7700K.

The only problem here is that you cannot use your existing LGA1151 motherboards in order to install the new CPUs. But a CPU like the 8700K gets you more performance that justifies the motherboards extra spending.

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