I ain't quite out of the woods with errors yet - but it's been a fun experience.
The most concerning one was when the motherboard was trying to read a boot device that wasn't there (afaik), so the only thing that loaded was a blank screen and _ cursor. That one persisted for a couple of restarts, and then I figured both the PC and me could do with some sleep - tried again the next day and everything worked. 🤷♂️
Fanspeed is about half the RPM it was before - although the system is still louder than I'd ideally like.
I'll create some new threads to deal with the Sleep / Startup problems I'm occasionally getting.