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

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Coffee Lake: an odd 14nm halfway generation

Coffee Lake, as introduced earlier this week, is a somewhat strange generation of processors, which were never scheduled and only appeared on Intel roadmaps relatively recently. 

For a long time Intel's strategy has been straightforward: when they started with the Core-processors, they also used the so-called tick-tock strategy, which means that a new generation of processors were released every year. These would either have a new architecture based on an existing production procedure, or a new production procedure with an existing architecture. The 2nd generation Core (Sandy Bridge) was a tock: a new architecture based on the proven 32nm procedure. The 3rd generation Core (Ivy Bridge) used a comparable architecture, but was the first generation on a 22nm procedure. The 4th generation Core (Haswell) was a new architecture on that 22nm procedure, and with the 5th generation Core (Broadwell) Intel moved to a 14nm procedure. However, the metronome of the tick-tock strategy started to creak there, because Broadwell was originally only released for mobile chips; a full line-up of desktop-processors based on this generation was never released. In 2015 the 6th generation Core-processors (Skylake) followed with a new architecture at 14nm. 

For 2016 we should have seen a transition to a new production procedure, in the form of 10nm Cannon Lake processors. Instead of this, Intel stated that the development of this new 10nm procedure was too difficult, which meant they had to get off their tick-tock strategy. From this point onward Intel would take more time introducing new procedures: after a traditional "tick" they would release a further improved version of the existing architecture based on the existing procedure. Because of this the 7th generation Core processors, Kaby Lake, were introduced last year. These were an improved version of the Skylake processors on an optimized 14nm procedure, called 14nm+ by Intel.  

Therefore Kaby Lake was already a "halfway generation", but still Intel is not yet ready to take the step to 10nm. Because of this they had to introduce a new generation with Coffee Lake, which was not found on any roadmaps originally. In terms of architecture these processors are practically identical to Kaby Lake (which was practically identical to Skylake), with the caveat that there are now chips with six instead of four cores. Coffee Lake is still produced using the 14nm procedure, but an even more optimized version of it, titled 14nm++. According to Intel these optimizations make it possible that the six cores stay within the TDP of previous quad-core processors (although the clock frequencies do have to be lowered for that, as we will see on the next page). As successor of Coffee Lake we finally see Cannon Lake, the first 10nm chips. Cannon Lake will be followed by Ice Lake: another new architecture. 

Coffee Lake is produced using a further optimized 14nm procedure.

8th generation Core: marketing generation ≠ chip generation

Not just the fact that this is a second halfway generation is remarkable; there is something strange about all 8th generation Core processors. Up until this point there was a clear one-on-one relationship between a marketing generation (read: model numbers) and a technical generation processors. The 2nd generation Core were Sandy Bridge processors, the 3rd generation Core was Ivy Bridge, the 4th was Haswell, the 5th Broadwell, the 6th Skylake and the the 7th generation was Kaby Lake. This changes now. 

Within the 8th generation Core-processors Intel is going to combine three technical chip-generations. Traditionally Intel creates four chip-types within a generation; S-series for desktops, all-in-ones and mini-PCs (35-110W TDP), H-series for fast laptops (35-45W TDP), U-series for thin laptops / Ultrabooks (15W TDP) and Y-series for tablets, 2-in-1s and the thinnest laptops (less than 10W TDP). In August the first 8th generation U-series processors were introduced and they are based on the same Kaby Lake generation as the 7th generation Core and are called Kaby Lake Refresh. The S-series introduced this week are Coffee Lake and the same goes for the H-series chips that will follow at a later date. However, the Y-series chips within the 8th generation Core will be the first processors based on the 10nm Cannon Lake generation. 

8th gen. Core TDP range Target audience Architecture Procedure
S-series 35 - 110 watt Desktops, All-in-Ones, Mini-PCs Coffee Lake 14nm++
H-series 35 - 45 watt Fast laptops Coffee Lake 14nm++
U-series 15 watt Thin laptops / Ultrabooks Kaby Lake 14nm+
Y-series < 10 watt Tablets, 2-in-1s, thinnest laptops Cannon Lake 10nm

Because of this it is not exactly clear what the next series of processors, 9th generation Core, will look like. Will Cannon Lake actually come to the desktop, or will the 9th generation Core be based on Ice Lake and make everything coherent again ? At the earliest we can expect answers to these questions late next year. 


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. £249.99
8 shops, 6x 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. £279.98
9 shops, 8x 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. £428.98
9 shops, 7x stock

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