Did you try AMD Mem Tweak XL to reduce mvddc & mvddci? Does it work?
Never tried, what I do to reduce temperature is set my fans 70% and leave my case open
It's very confusing about bios mod and memory voltage on these models, some people said that Gigabyte rx 5700xt are hard to bios mod because these cards are locked and won't turn on with biosmod, and I never find a way to reduce the voltage of ram, you can search on google and there's a lot of confusing information about