A sale can be a powerful and dangerous thing!  The 8700K was on sale at the local Central Computers for $350 and wound up an impulse purchase.  Of course it also requires a Z370 board because curse you Intel!, so that part sucked.

Anyway, the TL;DR is 8700K = hotter 6 core 7700K

The good news is this part easily went right to 4.9Ghz with no tweaking whereas the outgoing 7700K had a hard time staying stable over 4.5Ghz but with tweaking was able to survive benching at 4.7Ghz.   The bad news is an 8700K@4.9Ghz is the literal hotness.  The H100i v2 with fans set to “jet engine” struggles to keep it at 95C with all cores sync’d at 4.9Ghz under Prime95 small FFT, max heat, torture test.  Of course most people don’t use their computer to crunch zillions of small primes 24×7.  Real world even CPU intensive gaming maxes at around 72C or so.  Not horrible at all for a 6 core.

Single threaded performance is 7700K level plus a tiny bit more for the extra o’clock ceiling.  Z370 is so much like Z270 that the Maximus X Code dropped in place of the Maximus IX Code exactly (all cables, connectors, mounts, etc in exact same spots).  If you look twice you’d get confused which is even which.

Couple of benchies to demonstrate the sameness. RotTR, for reference, the 7700K at 4.7 pulled 112.65:

Metro, my nemesis.  7700K at 4.7 pulled 54fps so again, couple frames better mainly due to extra 200Mhz:

GTAV.  Here we see a pretty big difference.  As a refresher, the 7700K @ 4.7:

Frames Per Second (Higher is better)

Min,         Max,            Avg
Pass 0, 8.391803, 92.961838, 74.745102
Pass 1, 22.118397, 89.757729, 62.214157
Pass 2, 16.138762, 122.041451, 81.452080
Pass 3, 52.432972, 139.942307, 96.265266
Pass 4, 12.801882, 155.805099, 74.428955

Time in milliseconds(ms). (Lower is better).

Min,            Max,             Avg
Pass 0, 10.757102, 119.163910, 13.378803
Pass 1, 11.141102, 45.211235, 16.073511
Pass 2, 8.193937, 61.962624, 12.277158
Pass 3, 7.145802, 19.071968, 10.387962
Pass 4, 6.418275, 78.113518, 13.435632

And now the 8700K @ 4.9:

Frames Per Second (Higher is better)

Min,          Max,             Avg
Pass 0, 8.662753, 129.326706, 89.465530
Pass 1, 21.562950, 101.664055, 63.884972
Pass 2, 40.489765, 253.449829, 88.207367
Pass 3, 46.074432, 167.379852, 103.087448
Pass 4, 24.119125, 182.347137, 84.213165

Time in milliseconds(ms). (Lower is better).

Min,          Max,             Avg
Pass 0, 7.732355, 115.436745, 11.177489
Pass 1, 9.836318, 46.375843, 15.653133
Pass 2, 3.945554, 24.697599, 11.336922
Pass 3, 5.974435, 21.704012, 9.700502
Pass 4, 5.484046, 41.460873, 11.874628

This is a big improvement with the average (of averages) fps going from 77.4 on the 7700K and the average frametime going from 12.8ms to an average fps of 85.4 and an average frametime of 11.4ms on the 8700K.  About a 10% improvement

Last up is Ghost Recon where we see a small regression with the 7700K having managed to pull a bit more at 53.2fps:

Overall the 8700K is a nice part in that it pretty much keeps the bar at where the 7700K set it for single threaded perf, gives you two extra cores, and somehow provides a bit more OC headroom (or this was a lucky chip).  In exchange you pay a tax in terms of heat, but that’s physics.  What’s not physics is having to buy a new board yet again and still not get new features like TB3.  That part just sucks.  Overall though, now that it’s available in the 300s, the 8700K is a no brainer for anyone looking to build Intel right now.