Update: I replaced the PSU and the server has been running stable now for a few weeks. It appears this was a PSU related issue in the end.

Yeah.. this definitely was a nightmare, I am taking a few days off after this

Hi,
I stumbled across exactly the same issue that GPU and USB pcie cards would crash the VM if passed through together. It was already mentioned in an earlier reply that updating would fix the issue, and I just wanted to confirm that works for me as well. After running the following commands on my xcp-ng 8.2:

yum update
yum upgrade

everything works nicely now! Thanks!