hi
use amdcleanup tool
if you have flashed to the vega 64 bios use the registry edit file from the yourtube guide RX Vega 64 Undervolting Guide for Blockchain Drivers - Part 2.
go device manager and remember the driver key numbers under rx vega properties then details...
apply the registry edit with the driver key numbers... reboot
use overdrive nt and set the p7 1407 and 841 for voltage, memory set to 1100 and volts to 805
run cast, u should get 1700+ at least maybe 1970 depends on the individual card
i can confim the h110 PRO btc+ handles 7 vegas and rx480 no problems @ 1240w
ill try 8 tomorrow night