While this is happening, the power button is completely unresponsive; no matter how long I hold it down, the computer won't shut off (fans, lights etc. all stay on), so I'm forced to turn it off with the hardware switch on the PSU.
Initially this problem was accompanied by a burning smell, so combined with the video signal going out I assumed it was the video card. I have since bought a brand new video card and the computer is failing in the exact same way, so I'm assuming it's something else. I'm not 100% sure if I can still smell burning when this happens after replacing the video card, but if there is a smell it's now very faint. In any event I was never able to tell where in the case it was coming from.
Again, the fans and lights all stay on and the computer sounds like it's acting normally (in terms of component noises; I can't get the computer up and running to the point where I could test audio yet, although I'll check that if I manage). The DVD drive still opens and closes correctly, even though the power button is unresponsive.
Personally, I'm out of ideas. I'm 95% sure it's not the video card unless the new one decided to fail in the first half hour the same way as the old one. I doubt it's the power supply, since everything seems to stay on and the DVD drive still works, but maybe I'm wrong. And I have no idea how to distinguish between problems with the processor, motherboard or memory - I'm not completely tech illiterate, but this is the first time I've seen this and I don't have any older parts to swap out and test with.
Edited by quetz32, 09 May 2012 - 03:17 AM.