Strange Video Driver Pixelation Problem

[Jon Grant]

I had something similar on an old laptop, the corruption was even
visible on the BIOS screen during bootup etc. Same on Windows.
letting the hardware cool down and restarting after got it working
again.  Could be the same for you?

Have you run memtest to see if your memory is ok? Is it a unified RAM
gfx onboard chipset? you don't say which driver you are using, but
perhaps you can switch to the "vesa" one and see if it is okay in
that. I had to do that for an old Radion card that wasn't supported by
xorg a while ago myself.

Kind regards, Jon