Intel Core i7 8700K / i5 8600K / i5 8400 'Coffee Lake' review: affordable six cores!

More cores for the same price!



This week Intel introduced their 8th generation Core-processors for desktop PCs, code name Coffee Lake. While the performance gain seemed to get smaller every time a new processor generation was released, Intel takes a big step this time. This is mostly because of the addition of more cores. For the first time Intel's mainstream platform (Socket 1151) offers Core i7 processors with 6 cores and Core i3 processors with 4 cores. In this review you can find the effect that this addition has on the performance, and a comparison with the previous generation. We extensively tested the new Core i7 8700K, Core i5 8600K and Core i5 8400


We need to go back more than 10 years, to January 2007, when Intel introduced an affordable quad-core processor for the first time with the Core 2 Quad Q6600. Two years later, in 2009, Intel released their "Core series"-processors, which made a clear distinction between affordable "mainstream" desktop processors (socket 115x) and more expensive high-end processors (Socket 1366 and later 2011 and 2066) with Core i7s, i5s and i3s. Generation upon generation the maximum amount of cores was limited to four with the mainstream platform. Nevertheless the higher clock frequencies, new instruction set extensions and different architecture improvements let Intel introduce faster processor generations every year. However, the last few years the performance increase was limited to about 5 to 10 percent from generation to generation. This meant that more and more hardware enthusiasts did not have a reason to replace a processor of a few years old for a new model. 

Today, with the 8th generation Core-processors, Intel finally takes a big step forward again. Under the code name Coffee Lake, Core i7 and Core i5 processors are "upgraded" from four to six cores. The new Core i7 8700K and Core i5 8600K, successors to the popular Core i7 7700K and Core i5 7600K CPUs, offer 50% more cores at a comparable price. The cheaper i3 processors even go from two to four cores with the new generation!

We will probably never know whether Intel was always planning to take the step to six cores for the mainstream platform in 2017, or if this is (in part) because of the increased competition from AMD with their Ryzen 6- and 8-core CPUs in this price segment. Looking at old roadmaps, we do know that Coffee Lake was not originally planned by Intel. In any case: this generation is a bigger step forwards than we have seen in years. 

The new processors use the same Socket 1151 processor socket as Intel's existing 6th generation Core Skylake and 7th generation Core Kaby Lake desktop processors. However, the CPUs are not compatible with existing motherboards. Together with the new CPUs, Intel introduced a new chipset: the Intel Z370. Various motherboard manufacturers are releasing new motherboards based on this chipset. We will cover these first Z370 motherboards extensively in a separate article. 

As stated before, we will present our test results of the new Core i7 8700K, Core i5 8600K and Core i5 8400 in this article. Before we take a look at the benchmarks, as usual we first dive into the technology!

This review was written with editorial contributions by Reinoud Dik and Tomas Hochstenbach. Photography by Jacob Jan Kuipers and Joost Verhelst. 


three products discussed in this review

  Product Lowest price

Intel Core i5 8400 Boxed

Socket 1151, 2.8 GHz, 6 cores, 65 W, 14 nm, Integrated graphics

Specifications Test results Reviews Prices


Avg. £283.47
6 shops, 5x stock

Intel Core i5 8600K Boxed

Socket 1151, 3.6 GHz, 6 cores, 95 W, 14 nm, Integrated graphics

Specifications Test results Reviews Prices


Avg. £312.78
7 shops, 6x stock

Intel Core i7 8700K Boxed

Socket 1151, 3.7 GHz, 6 cores, 95 W, 14 nm, Integrated graphics

Specifications Test results Reviews Prices


Avg. £458.99
8 shops, 6x stock

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