https://arstechnica.com/gadgets/2017/10/intel-coffee-lake-8700k-review/

For those that game, there's no better processor than Intel's Coffee Lake Core i7-8700K. Where its predecessor, the Kaby Lake Core i7-7700K, offered little more than slightly higher clock speeds and a way to decode DRM-laden 4K video over 2015's 6700K, the 8700K boosts performance with six cores, 12 threads, and a mighty 4.7GHz boost clock, the fastest out-of-the-box clock speed Intel has ever produced. The 8700K handles content creation admirably too, its high clock speed partly compensating for the two extra cores of AMD's Ryzen 7.

But it's not an outright smash. Much like Intel's Skylake-X i9 processors, there are signs that the 8700K was rushed to combat a resurgent AMD, as well as to fill the gap created by the now delayed 10nm Cannon Lake architecture. Reaching such high clock speeds across six cores has dramatically increased power consumption, and made managing heat a headache. Overclocking isn't for the faint hearted, or at least those without a substantial cooling setup. And, despite being based on an architecture that stretches back to Skylake, Coffee Lake requires a new motherboard, turning what might have been a compelling upgrade, even for Kaby Lake owners, into a far more considered purchase.