GPU HANG ecode 7:1:85fffffc, in gnome-shell, KDE/KWin
Within about 5 minutes of logging in via GDM to the GNOME shell (also on KDE Plasma), my entire desktop will freeze (sometimes the mouse will be able to move), usually with tearing and cause an almost epilepsy-triggering rapid flashing of any elements on screen that happened to be moving at the time, for example switching in and out of apps or going into applications in the GNOME desktop menu. It can sometimes happen almost instantly, but usually within about 10 minutes of just using the desktop normally.
Killing GDM and re-logging in causes a black screen and I have no choice but to reboot. Reproducible on linux-zen (5.10) and latest drm-tip on Arch Linux. Going back to linux-lts on 5.4 remedies the problem, but I am met by another GPU hang bug which was fixed in 5.6 I believe, so I am using that right now.
I am on an i5-3470, currently connected via VGA but also reproducible on DVI. Attached is a video of the issue, and logs on linux-zen and drm-tip. video_2021-01-19_22-21-49 error-drm-tip.txt error-linux-zen.txt