My computer just fizzed for about 3 seconds, then went BANG and switched right off, leaving a smell of burning. What's the most likely fault so I know what to replace? When I try to switch it back on, I get a beep from the motherboard. I don't think it would be the power supply, because I'm getting that beep when I turn it on. Do CPU's go BANG when they blow? Anyone had anything similar happen to them?

can you tell us the beep pattern? maybe it's just your video card that's fried... although it could still be your board or even the power supply yet. You could check the voltage (under load) of the power supply to be sure. But if you can, post the beep code you get, be it something like 2 short and one long, or repeating short beeps, that all makes a difference, and we can help better.

I wouldn't know where to start with checking the voltage of the power supply, but I'm just getting one single beep as if it's booting up normally. Would this suggest to you that the video card has had its day? It's a Geforce MX440. Do they go BANG?

If you heard a bang and smelled burning, a visual inspection in the box should show some damage somewhere.

you get one beep, and it appears to be booting... hmmm... well, I would suspect that video card first. if you have another one around, even a pci card, give that a shot, and see what happens. As EC said, take a look inside the case, and see if you can see some component that looks damaged... although it's not always visible, but if you could hear it, you should be able to see it.

Try posting in the general hardware forum. Here's a tip though, use your nose. Sandman

Having checked inside the case, there's no evidence of any kind of damage to the video card or anywhere else, but there is a brown dusty residue around the CPU fan that comes away easily to the touch (although that could already have been there, as I've never cleaned it - oops). The smell has now cleared so I can't tell exactly where it came from. I am (was) running an Athlon XP2000.