The silicon lottery binning figures for i7 8700k's:
As of 11/11/17, 100% of tested 8700Ks were able to hit 4.9GHz or greater. ( 1.387V Vcore -2 AVX Offset)
As of 11/11/17, the top 81% of tested 8700Ks were able to hit 5.0GHz or greater. (1.40V Vcore , -2 AVX Offset)
As of 11/11/17, the top 58% of tested 8700Ks were able to hit 5.1GHz or greater. (1.412V Vcore , -2 AVX Offset)
As of 11/11/17, the top 30% of tested 8700Ks were able to hit 5.2GHz or greater. (1.425V Vcore , -2 AVX Offset)
As of 11/11/17, the top 6% of tested 8700Ks were able to hit 5.3GHz or greater.( 1.437V Vcore , -2 AVX Offset)
That's from 100+ CPUs
As much as the "enthusiast" in me would love a 5Ghz capable chip it sort of kills it for me knowing that once your retailer has gone down the binning road that it's pretty much guaranteed all the sweet CPU's have been snagged and pitched onto the market at a premium price and therefore any "normal" chip from that reseller is going to be a dog.