Thanks Daniel,
1) I uninstalled xserver-xorg-video-intel. No change.
2) I noticed that. 18.04 and Debian works fine on same machine.
Using a recent installation of 20.04 desktop with updates but little to
no changes from stock:
5.4.0-42-generic WORKS FINE on /dev/sda1:
5.8.0-38-generic on /dev/
Thanks for the bug report. A few thoughts:
1. xserver-xorg-video-intel is old and not supported. Please uninstall
it to make sure you're using the newer default driver ('modesetting').
2. Your kernel log shows constant hardware errors from the 'Intel
Corporation 8 Series PCI Express Root Port 3':
