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The best, fastest gaming CPU money can buy: Intel Core i7 6700K

The fastest quad beats Intel's older six and eight-core chips.

The battle royale: if money is no object, what is the fastest gaming CPU money can buy? It's a question we recently set out to answer and the results were quite remarkable. Out of all of Intel's current top-of-the-line processors, it is the cheapest offering that is the most powerful - the Core i7 6700K.

First up though, a bit of background. Intel divides its processors into mainstream and enthusiast lines. The former gives us dual and quad-core chips, while the latter ramps that up to six and eight-core processors aimed at the high-level enthusiast. However, adding a wrinkle to the situation is the fact that the mainstream sector gets new CPU architectures first, leaving the many-core enthusiast line to catch up a year or so later.

Making things even more complicated is the fact that Intel's latest mainstream architecture - codenamed Skylake - is actually two generations beyond the Haswell tech found in the enthusiast line. Haswell's successor - Broadwell - only received a minimal desktop release, with Intel skipping ahead to Skylake instead. And that may well explain many of the results you are about to see here. Despite most modern games supporting eight or more processing threads, it is Intel's quad-core chip that beats out the competition in most of the benchmarks here.

We decided to do two benchmark runs here using the Core i7 6700K quad-core chip, the Core i7 5820K six-core processor and finally, the $1000 monster, the eight-core i7 5960X. To begin with, we used the same methodology we used with all of our prior CPU tests - we paired the processors with an overclocked Titan X running at 1080p, but in this case we backed it with high-speed DDR4 RAM running at 3000MHz (3200MHz in the case of the many-core enthusiast chips). However, we supplemented that with further tests running with two graphics cards too - in this case, two GTX 980s running in SLI.

Note that we tested 'stock' non-overclocked CPU performance, but all enthusiast boards with XMP memory overclocking enabled also tend to activate 'enhanced Turbo', which boosts all CPU cores to maximum stock speeds. That'll be 4.2GH for the 6700K, 3.6GHz for the 5820K and 3.5GHz for the 5960X.

Rich spent the good part of a week benchmarking these top-of-the-line CPUs - check out single-card and multi-GPU results here with both stock and overclocking performance tested.

Titan X OC (Average FPS) i7 6700K/ 3000MHz DDR4 i7 6700K 4.6GHz/ 3000MHz DDR4 i7 5820K/ 3200MHz DDR4 i7 5820K 4.6GHz/ 3200MHz DDR4 i7 5960X/ 3200MHz DDR4 i7 5960X 4.4GHz/ 3200MHz DDR4
Assassin's Creed Unity, Ultra High, FXAA 88.4 89.3 84.2 84.6 84.4 84.6
Crysis 3, Very High, SMAA 124.4 124.7 119.4 120.8 124.4 125.5
Grand Theft Auto 5, Ultra, no MSAA 89.4 92.7 79.0 86.7 81.9 90.3
Far Cry 4, Ultra, SMAA 120.4 125.9 92.0 104.5 84.8 95.4
Shadow of Mordor, Ultra, FXAA 141.0 142.9 139.6 139.5 139.9 139.9
The Witcher 3, Ultra, HairWorks Off, Custom AA 105.8 106.4 103.4 103.4 103.5 103.8

Order our tested Core i7 processors from Amazon with free shipping:

What's clear is that games depend more on the additional per-core power of the latest Skylake technology than they do on the additional cores offered by the Haswell-E enthusiast chips. Equally clear is that for the most part, moving up from six to eight cores offers only the very slightest of improvements. Without an overclock in place, the 6700K is fastest on all but one game - Crysis 3, where it requires the eight-core 5960X to beat it, a chip that costs three times as much.

Proving that single-core performance is still king is Far Cry 4, where the Core i7 6700K is far, far ahead of the competition - owing to the fact that although it uses up to eight threads, all of them are powered by one dominant core. However, other results are essentially margin of error stuff.

Far Cry aside, there is no absolutely conclusive win here, but the bottom line is straightforward enough: it's the cheapest Core i7 processor tested here that actually offers the strongest performance overall. So the question is, does that situation change at all when migrating to a dual graphics card set-up? Let's roll out the two GTX 980s and see what happens.

sli
Thanks to an assist from MSI, we were able to push these three CPUs to their limits via a GTX 980 dual-GPU set-up.
GTX 980 SLI (Average FPS) i7 6700K/ 3000MHz DDR4 i7 6700K 4.6GHz/ 3000MHz DDR4 i7 5820K/ 3200MHz DDR4 i7 5820K 4.6GHz/ 3200MHz DDR4 i7 5960X/ 3200MHz DDR4 i7 5960X 4.4GHz/ 3200MHz DDR4
Assassin's Creed Unity, Ultra High, FXAA 107.7 108.9 104.3 104.9 104.1 104.2
Crysis 3, Very High, SMAA 117.6 124.6 119.7 122.6 120.7 123.0
Grand Theft Auto 5, Ultra, no MSAA 88.0 93.5 77.9 89.6 80.9 92.6
Far Cry 4, Ultra, SMAA 124.3 128.0 91.7 103.11 85.8 98.6
Shadow of Mordor, Ultra, FXAA 167.3 170.3 160.0 167.0 165.7 168.1
The Witcher 3, Ultra, HairWorks Off, Custom AA 113.2 116.5 108.2 110.3 108.4 109.2

Aside from notable increases in performance in Shadow of Mordor and Assassin's Creed Unity, the overall takeaway here is that CPU performance is the limiting factor here, as our two-card results aren't enormously improved over our single-card testing. Now, the X99 platform that hosts the i7 5820K and i7 5960X do support higher levels of PCI Express bandwidth, meaning that more graphics cards can be run in parallel with the more expensive CPUs. However, even two cards don't scale particularly well while three or more really are a waste of money.

Skylake's Z170 chipset may not have the same levels of PCI Express bandwidth, but it can easily cope with two graphics cards and as you can see from the results, the domination of the cheapest i7 remains much the same. In fact, it's ever-so-slightly improved its standing from the Titan X testing.

So, in purely gaming terms, the Core i7 6700K is the fastest gaming CPU money can buy. However, in other tasks that scale across multiple cores - video encoding, for example - the many-core chips really are tested and can completely blow away the later Skylake chip. Our recommendation is pretty straightforward then - get the 6700K if your system is going to be used as an out-and-out games machine, but do consider the 5820K if productivity is part and parcel of your PC requirements. You may lose a little in terms of gaming performance, but you gain a whole lot more for tasks like multimedia creation and pure number-crunching.

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About the author

Richard Leadbetter

Richard Leadbetter

Technology Editor, Digital Foundry  |  digitalfoundry

Rich has been a games journalist since the days of 16-bit and specialises in technical analysis. He's commonly known around Eurogamer as the Blacksmith of the Future.

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