There has been a reoccurring issue with my computer (about 1.5 years old now) where I usually cannot work for more than 10 minutes without the whole thing crashing. Usually what will happen is the screen will flash, coloured lines will appear all over the screen and finally the whole thing just seems to shut down.

I have taken some measures to pinpoint exactly where the problem might come from, such as cleaning out the inside & fans (so its not a heat issue), downloading all the latest software for the motherboard [ASUS (P5S800)] and video card [nVidia], running a scan for viruses, and completely reinstalling windows XP [all of these measures seemed to clear the problem for at least a short period of time but it keeps coming back].

My brother has the exact same computer as me (built entirely using the same hardware) and he hasn’t had this problem, so I’m beginning to think it might be an issue with maybe my ASUS motherboard being faulty.

Has this ever happened before, and what could be the reason behind this?

I've had the same problem previously, and it was because of the power supply. I tried to take out the power cable from the motherboard, and it was basically welded to the motherboard. Possibly from a power surge (I now always use a surge protector!). So poor or uneven power to your GPU may cause such a problem. Are there any extra power cables going to your graphics card? If so make sure they're in securely.

Try swapping the power supply with your brothers, to see if that helps.

If he's a really nice brother, he may let you swap parts bit by bit to try and narrow down what the cause of the problem is.

Failing this, try and see if the temperature is reporting correctly on your graphics card. If it is showing as too high (even though it may not be), then the temperature sensor might not be correct.

Good Luck!

I dont think memory is an issue because the problem happens sometimes before the computer even has a chance to boot up (ie: when the windows logo first appears).
I've switched vid cards with my bro before and no dice. Still the same problem ... so I guess that kinda narrows the problem down a bit.

Hmm interesting. As I said I've swapped the video card before, and unfortunately this caused 0 change.
I've never thought about it being a power issue. I'll definitely look into it with either my dad or my brother (I'm pretty hopeless at technical computer stuff). But in the long run I'm prepared to fork out $70AUS for a new motherboard if that solves the problem, cos the computer is awesome apart from this dumb little problem.
Thankies!