I recently got my hands on an 8700K (finally!) and a Strix Z370-I. The processor is pretty solid at 1.3V and 4.9GHz; load power consumption for the rig (960 PRO, GTX 1070) is about 190W under Prime 95. However, there seems to be a bug (feature?) - at high temperatures, the VRM's seem to raise the Vcore to well above what I've requested in the BIOS. This is evident on the power meter - power consumption jumps from 190W to 230W+. Furthermore, at higher Vcore's and frequencies (1.4V, 5GHz), these voltage excursions lead to thermal runaway - power consumption will jump to 290W, leading to rapid overheating of the VRM's and consequent shutdown.
Looking around the forums it seems like this kind of behavior is present across the entire ROG line, and has something to do with SVID and LLC. I've made all the appropriate adjustments in the BIOS (optimistic SVID, CPU DC load line set to 0.01, etc). Is there a BIOS fix that will make the automatic voltage adjustments less aggressive, or even better, force adaptive voltage to output a fixed voltage under load?