Build Issues... - Help me solve a weird problem

Specs:

  • AMD 5800X
  • AMD 7900 XTX
  • Asus ROG-Strix Gaming X570-I
  • Corsair RM1000x
  • 32GB GSKILL TRIDENTZ

So I recently upgraded my gfx card to a 7900XTX. I had been running my previous build on a 750W Corsair SF750, but given the upgraded I bought a RM1000X to give me a little more headroom, following a crash whilst gaming.

Installed the new PSU and everything was running fine. Turn off the PC, turn it back on a day later - will not boot, shows DRAM light on mobo. ...reset CMOS and re-seated the RAM - works fine again. Turn off... have to reset CMOS and reseat RAM again before it will boot.

Ran memtest - RAM is fine. Ran OCCT processor is fine. Am currently running the Power test on OCCT - again, no errors.

So what's left? The mobo? Surely if the mobo was dead, it wouldn't boot at all, no? I have read somewhere it might be a dead CMOS battery, but not sure how/why this would be the case given that when I reset it, it works again.

Incidentally, the PC seems fine when I restart, but I have to go through the process of resetting CMOS and reseating the RAM after shutting down and leaving for some time.

Thoughts? Suggestions?