How to investigate XFCE desktop interface completely freezing with remote SSH access?

Running into a mysterious problem I’ve been trying to narrow down over this weekend. Fully tested memory and stress-tested system while carefully monitoring various temps. Everything seems fine. But, randomly on a fresh XFCE LTS installation I am encountering total desktop interface freezes. Everything becomes unresponsive to clicking and no window contents update, then a very short time later (or immediately) the mouse cursor stops entirely.

At first I thought it was the entire system freezing, so I set up SSH access and have been able to stay connected via SSH from a different machine. Now I am trying to figure out a way to re-start the desktop interface via SSH. I tried servicectl restart lightdm but that just hangs.

Some online searches led to a setting for processor.cstate to 2, which I did, and that’s active but has not stopped the freezes.

Have taken a look at the journalctl log but don’t see anything obviously the culprit yet.

What logs should I be watching?

Can I enable those non-X tty interfaces somehow so I can toggle over to one while it’s frozen?

Ideas WELCOME would love some tips on debugging further.

Maybe a graphics driver? Mine is currently set to the nvidia driver that the installer auto-selected for my GTX 1650 card.