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Intel 8th Generation Core i7 8700K & Core i5 8400 Review


Intel 8th Generation Core i7 8700K & Core i5 8400 Conclusion:

When you look at the results delivered by the Core i7 8700K and Core i5 8400, it's clear that Intel's new architecture has got a tremendous upside in performance. When compared to Intel's Kaby Lake and Skylake 4C/8T processors, the added core count of the Core i7 8700K is easily outpacing the mid-range stack. When you compare the performance delivered by the Core i7 8700K to AMD's R5 1600X in a direct comparison of six-core / 12 thread processors, there really is not much of a comparison when you look at just the performance deltas. In fact, the Core i7 8700K outperforms or delivers comparable results with the 8C/16T R7 1800X, R7 1700X, and R7 1700 in just about every single benchmark. The sky-high Turbo Boost clock speed of 4.7GHz on the i7 8700K allows it to excel in all of the single and lightly threaded benchmarks, posting several bests in the results.

I was pleasantly surprised to see that these new processors delivered such an increase in performance with the addition of just two cores. The Core i5 8400 was equally impressive when you compare its performance to that of the 4C/8T R5 1500X. In every test but two, the i5 8400 was the higher performing processor. Pretty impressive for a chip that can only work six threads at a time versus eight. It just goes to show the IPC improvements made by Intel, along with the core count/core speed improvements. Optane memory is an added option to boost the performance and feel of your system. I will have an upcoming short article on Optane memory to explore this option, but it looks like a promising way to get that quicker feel.

Overclocking is going to allow you to get a bit more performance out of your hardware without an additional cash outlay. As I found out, overclocking a non-K-SKU chip let me get a few MHz worth of clock speed to add a bit of a measurable performance boost, but overall added only a little bit of gas to the system. Every little bit counts, right? Overclocking the Core i7 8700K was a bit easier and is much like overclocking any other Intel processor, with some little tweaks to use per core overclocking to get the most out of every core. I did not get the opportunity to fully explore this option, but will take a deeper dive once I work through the motherboard review to see just what this chip can do.

With an all-core overclock of 4862MHz on the i7 8700K, you can see that the performance scales nicely in most benchmarks. However, at stock speeds my test board kept the core clocks pretty high with an all-core clock speed of between 44400-4600MHz. It's tough to gain a lot over that, but is definitely doable.

Intel says that we can see up to 25% improvements in gaming performance with this architecture. I did not see that much of a boost in the games I test, but did see some pretty measurable increases. The FPS increases in Hitman were sick. After about 30 runs and several driver changes, the FPS performance stayed within a 2FPS range of my final results. In The Division, the FPS deltas over the rest of the field were not that great, but were the highest FPS levels I have seen of all the CPU's I have tested this year. Yet another impressive feat.

The one thing that might be a deal breaker with this generation is that these processors are not an upgrade path for those out there with Intel 1 or 2 Series motherboards. You will need to upgrade to a new LGA socket 1151 motherboard with a Z370 chipset to be able to use a Coffee Lake series i7, i5, or i3 processor. Motherboard pricing is going to be comparable to 2 Series pricing, but it's just one of those inflection points that make you decide to sell what you have to move up or sit tight. Pretty much across the board, 8th Gen is faster.

Now when you look at the difference between AMD's Ryzen offerings, the performance/cost discussion gets a bit more complex. When you look at a Ryzen 1600X and a high-end board, you are looking at a processor cost of $200 and a motherboard cost of ~ $200. Change to an R7 1800X and you are at $600. Then there's the Core i7 8700K at $359 with a $200 motherboard. You are about $160 higher than the R5 1600X combo and about $40 less than the R7 1800X combo. It gets to be a decision you as the consumer will need to make in the end. Any way you look at it, the Coffee Lake architecture is going to be an interesting comparison with the launch of a quad-core i3, the six-core i5 series, and six-core i7 processors.



  • Gaming performance 
  • Overall performance
  • Optane memory ready
  • Overclocking K-SKU


  • Requires new 3 Series motherboard
OCC Gold

  1. Intel 8th Generation Core i7 8700K & Core i5 8400: Introduction & Closer Look
  2. Intel 8th Generation Core i7 8700K & Core i5 8400: Specifications & Features
  3. Intel 8th Generation Core i7 8700K & Core i5 8400 Testing: Setup & Overclocking
  4. Intel 8th Generation Core i7 8700K & Core i5 8400 Testing: Apophysis, WinRAR, Geekbench 4, Bibble 5
  5. Intel 8th Generation Core i7 8700K & Core i5 8400 Testing: Office 2016, POV-Ray, HandBrake
  6. Intel 8th Generation Core i7 8700K & Core i5 8400 Testing: SiSoft Sandra, AIDA 64
  7. Intel 8th Generation Core i7 8700K & Core i5 8400 Testing: Cinebench R15, HWBot X265 Benchmark, PCMark 8.2
  8. Intel 8th Generation Core i7 8700K & Core i5 8400 Testing: Gaming
  9. Intel 8th Generation Core i7 8700K & Core i5 8400: Conclusion
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