Originally Posted by CaptNKILL
Sort of sounds like artifacting from heat or a defective video card. I had stuff like this in Half-Life 2 and had to lower my overclock a little bit, it was the only game that this happened in.
If you arent overclocking then its possible the card is just dieing\defective. Wait for some other opinions though, Ive never experienced this exact problem myself.
Thats what can i think of as well . Doom3 is so sensitive & hardware demanding that even an old PSU can cause artifacts in it . thats what i had actually .