The next version of Intel's processor microarchitecture is called Kaby Lake, which forms the successor to Skylake and chips using it are just now just starting to appear. Kaby Lake is a 14nm processor with very few changes to the CPU architecture compared to Skylake. It's best to view it as a refinement, promising faster CPU clock speed, higher Turbo frequencies, and a new graphics architecture allowing for better 3D and 4K performance.
A small improvement in performance across the board may not be enough to tempt those already running Skylake chips into an upgrade. However, Kaby Lake looks to have an ace up its sleeve: it's great for overclocking.
The highest performing Kaby Lake processor Intel currently plans to offer is the Core i7-7700K. It runs at a stock clock speed of 4.2GHz, with Turbo increasing that to 4.5GHz. That's impressive, but as HotHardware reports, Russian website OCLab (translated) managed to get hold of a 7700K and decided to see what it could really do.
Using liquid nitrogen cooling, they placed the Kaby Lake chip in a Z170 motherboard and started ramping up the speed. When they were done, the chip was running steady at 7022.96MHz, so 7GHz!
Typically with these massive overclocks, unless you're willing to have an abundant supply of liquid nitrogen on hand you'll never achieve them for your desktop PC. They also require all but one of the cores on the chip be shut down, rendering the CPU single core. However, here again the Kaby Lake chip impressed as that 7GHz speed was achieved with two cores still running.
There's still some headroom left to increase the overclock speed. I mentioned the Z170 motherboard above as it's an older board. Kaby Lake is getting its own line of motherboards built specifically to support it, meaning there's potential to go quicker still once they are available.
So if you enjoy overclocking your gaming PC, and especially if you are using liquid cooling, a Kaby Lake processor should definitely be on your buy list. While you won't hit 7GHz, over 5GHz should be easily achievable, and with some tweaks I'm guessing 6GHz could be attainable without turning off any of the cores.
I suspect we'll get quite a few of these overclocking tests as more 7th gen Intel processors are shipped out. Hopefully they prove OCLab wasn't lucky with the processor it got and Kaby Lake chips are fantastic for overclocking across the board.