I have had the same experience as you (been watching this board for a week now), except the NIC, my board has a 2.5gb but is running at 1gb in unraid.
I am running an asrock z690 pro and i7 12700k.
I found the hangup/crash was when plex was transcoding hevc.
I did however leave the unraid logging open and waited for a crash and noticed an error regarding receiving a message from the past when it did crash. (In hindsight I should have taken a screenshot)
Still hoping someone can find a fix that is better than removing /dev/dri and losing HW transcoding.
I have yet to do a memtest yet, but am planning to this weekend.