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

More cores for the same price!

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Nothing new aside from extra cores

Today it is time for the first 8th generation Core-processors for desktops. Intel introduced six models, all internally based on the Coffee Lake-S chip, on which Intel does not want to release any information about things like chip size and transistor count. 

Coffee Lake-S is, as described on the previous page, basically best defined as a Kaby Lake chip, only with six instead of four cores, produced using a further optimized 14nm procedure. Nothing changed in regards to the architecture of the CPU-cores or the integrated GPU. The step from quad-core to 6-core might be a big one, but from a technical point of view this generation is pretty boring aside from that. 


A die shot of the Coffee Lake-S chip with the six cores in the middle and on the integrated GPU on the left.

Components

In the end the Coffee Lake-S chip consists of the following parts, which are all connected to each other using Intel's known ringbus architecture. First of all six CPU-cores with as usual 256 kB own L2-cache and a connected segment of 2 MB L3-cache that is shared by all cores (and is used to transfer data between cores). Because of the total amount of six cores the top model Coffee Lake chips have 6 x 2 = 12 MB shared L3-cache. 

iGPU

Coffee Lake has the exact same integrated GPU as Kaby Lake, which is now called UHD Graphics 630 by Intel instead of HD Graphics 630 because of the rise of Ultra HD-monitors. To be clear, aside from a slightly higher maximum clock frequency with the Core i7s this integrated GPU is identical. There is support for DirectX 12 and in terms of video Intel offers support for H.264 and (8- and 10-bit) H.265 decoding and encoding (via QuickSync). The VP9 video-codec is also supported, although 10-bit VP9 can only be decoded. Thanks to the support for DisplayPort 1.2 it is not a problem to connect a 4K / Ultra HD monitor, but native support for HDMI 2.0 is still absent (although this can be added using a converter chip). 

Memory controller

Coffee Lake also has a dual-channel DDR4 memory controller, identical to that of Kaby Lake, but now in the i7s and i5s it is officially validated to operate at DDR4 2666-speed. Last but not least the processors have a PCI-Express 3.0-controller with 20 lanes; four of these are used for the connection with the chipset and the remaining 16 can be used for connecting a graphics card. Other PCI-Express lanes (for example for PCIe SSDs) have to come out of the chipset. 


Compare

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

£175.98

Avg. £204.49
5 shops, no stock

Intel Core i5 8600K Boxed

Socket 1151, 3.6 GHz, 6 cores, 95 W, 14 nm, Integrated graphics, 0.055 Ah

Specifications Test results Reviews Prices

£269.99

Avg. £270.32
6 shops, 4x stock

Intel Core i7 8700K Boxed

Socket 1151, 3.7 GHz, 6 cores, 95 W, 14 nm, Integrated graphics, 0.055 Ah

Specifications Test results Reviews Prices

£395.99

Avg. £409.99
6 shops, 4x stock

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