Ok, so I've been having troubles on and off with my pc for a while, it's fairly outdated as I'm a broke *** uni student. Recently I went to a LAN with a few friends, I got there and set up but I was getting no signal to my monitor. Half an hour of playing around later it turned on and ran fine for the week I was there. So I get home, plug it all back in, no signal. Play around for a while and get an error in POST that overclocking failed (which there is none) to restore defaults etc. Reset BIOS defaults and tried booting to windows, get to the login screen and the colours go screwy and windows wont load any further. Reset, no signal, still no signal now.

Tested my monitor and the DVI cable and both are fine, replaced my mobo with a cheap crappy one ($50), tried and still the same problem. I borrowed a spare gfx card off a mate of mine, Gigabytes oc HD 5670 and still no luck. Tried swapping out RAM, nothing, checked the mobo battery and nothing. Plugged things in one at a time, poqwring on as I went, nothing. The power goes on, no POST beeps and no signal and there is an internal speaker. I'm wondering if it may be the PSU? Like I said my computer is old but I'm not sure...the PSU is a 400W with only a 12v and -12v combined at a lousy 10.5a...

The system is running a crappy P4 3.0ghz
2x512 sticks of Corsair ddr2 800 ram
Gigabyte oc HD 5670

Any help would be greatly appreciated.

Probably PSU components and has degraded overtime, so checking it out is worth a try. Especially if you are running one of the hottest CPUs of the olden days ... its a Prescott core right?

Yeah running Prescott. Could heat be abother factor? Could be why I'm not getting post but I'm not sure about the monitor signal? I'll check the PSU and see what happens.

Its worth checking i guess, because PSU efficiency do decrease overtime.