I undervolted my WC/LC Vega64 20-37mv and that lowers temps a touch and helps maintain boost clocks. The 20-37 part is the difference between Wattman and Afterburner. Afterburner seems to be a bit more stable using lower clocks hence the lower 37mv part.
Wattmann is a true piece of junk. Absolutely can not believe AMD even has it. Shit never holds clocks. Always goes to balanced mode after computer restarts. Might as well stop wasting time on wattman and let third party do the job. AMD has wasted a lot of time on features that are not needed and they can actually focus on other improvements. Wattman is one of those features with wasted time and effort. Let afterburner and trixx do their thing and just eliminate wattman.