Originally Posted by gamefoo21
Are you running your V64 on any kind of overclock?
Is it a blower monster?
I would really suggest looking at underclocking and undervolting it. The HBM on the 64 should be able to do 900mhz at 0.900V. I'd pull the core back to 1.1 or even 1.0Ghz. just to see if simply dropping the clocks helps it. Vega 56/64 were always best when you could slightly underclock them and undervolt them appropriately.
That would be my suggestion. It really sounds like it desperately needs a repaste/cleaning.
There is an issue with some of the bigger WUs for all AMD/ATI cards. Its a bug in AMD's OpenCL implementation and OpenMM is working on a solution on their end if they can find one.
Personally, my Vega64 runs just fine when it gets a smaller CV19 WU @ 1,800Mhz Core and 1035Mhz HBM2.