That's mostly way over my head, so I'll only mention three things:
1-I counted 6 stuck CPU entries in the log.
2-
That HP model was originally certified for 6 operating systems, none of which were Debian or derivations from Debian, as is Ubuntu.
3-Moving can rattle things. If you haven't reseated everything in an unlocked socket, I'd give that a go first, and same with any power connectors.