mh, did you already flashed the newest bios?
if yes - maybe wait 3-6 weeks until the new AGESA rolls out - maybe it fixes your problems
you could try a fresh install of Win10 20H2
20H2 is the latest Win10
do a fresh install of that - via a USB you created with current media creation tool
I had a similar issue with an older chipset board, Try the reinstall with only one RAM stick installed and then once installed, shut down and install the second. This was the only thing that fixed my system. I hope this helps.