Grapics Problem

[wanderer58]

Screen became distorted looks like small digital blocks. Same problem when in bios screen picture is unreadable.

Dell Xps 400
With a 6800gt video card
375 Power suppy

[#43 fan]

1 of three things. Videocard is bad (or overheating), Power Supply isn't providing enough power, or Monitor is going bad.
I'd check (or replace) the Power Supply first, then the videocard, then the Monitor.

[BipolarBill]

I would be sure that the video card fan is working and that it is free of dust bunnies.