ASUS Zenbook UX391
Fixing screen glitches
By default screen glitches will appear at some point, but the system is fully usable nevertheless. To fix this add intel_idle.max_cstate=4 to your boot options.
For GRUB you can edit /etc/default/grub, add intel_idle.max_cstate=4 to GRUB_CMDLINE_LINUX_DEFAULT and update grub with the new config.