https://www.techspot.com/review/1450-core-i7-vs-ryzen-5-hexa-core/page9.html
X399 is much better choice, you can simply use game mode for gaming and everything else for CPU. Either way 6 fastest cores is best choice for gaming, unless you are streaming BF1 (or any other CPU intensive game) while gaming R7 could be better choice than i7 8700K, but even i7 8700K should kill it. Specially, if you are going to OC to around 5GHz.
techspot did test i7 8700K 4,3GHz and it eats quite some power. Looks like i7 8700 will need more than good board to maintain 4,3GHz (or cheap fan over VRMs).
https://www.techspot.com/review/1497-intel-core-i7-8700k/page4.html
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But looks like you can get better P/W with OC.
Probably doesn't guarantee perfect stability, but no one will argue with it, if it achieves better clock and lower power and runs corona.
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