I haven't really posted or been active in the OC community in a long while. My last real build was in 2013 with a 5ghz 3770k and I haven't upgraded since then.
I ended up getting the itch and purchased a new motherboard, ram, and cpu. That being the Z390 Aorus Master and 9900KS.
I have two 9900KS in my possession, one which is being returned, but I figured I would share some of my findings here. Both chips require at least 1.33-1.34 volts to be stable in Prime95 with AVX offsets at 5ghz stock.
Your chances of overclocking to 5.1 and 5.2 are severely limited on a KS. Voltages may even be high on stock unless I am doing something completely wrong.