I tried the MemTest suite in Linux and it worked fine for about 15 minutes without errors. When I returned the screen was black. However, now after start up (prior to BIOS) sometimes I get a screen with a lot of dots (like Morse code) or garbled video.
Now, when I start I don't even get the BIOS screen but beep, beep, pause, beep, beep which makes me presume that the video card is damaged (GTX285). So I think either the video card is damaged or the motherboard is damaged and doesn't detect the video and/or memory. Both are expensive to replace, what can I do to pinpoint the problem?