5punk

Got home from work last night, fired up the PC and it imediately turned itself off, then started, then turned off, etc etc etc.

No POST, just constant start, restart... It worked that morning and no-one had been in to use it so I am a bit confused as to the problem.

All fans power up and start spinning, then just shut down again.

I'm thinking that either the MoBo is goosed or the PSU is having a fit...

I detached all peripherals (Fans, Hard Drives, Optical Drive etc) as well in case one of them was glitching but still getting the same problem.

MoBo is GigaByte EX5A-UDR3
PSU is Corsair TX 650W ATX

Any ideas before I go throwing money about

Option 1) HAMMERS!
Option 2) CIIJASIIE

Similar thing happened to me when my power supply was dying

Its only just a year old, would have expected the power supply to have lasted a bit longer than that... Don't want to be buying a new one if that isn't the problem.

My mate has a similar build PC to mine, may have to go round his and do some fettling

Pull all the ram out, then try starting it. I bet it'll post with the no ram beeps.

It doesn't seem to even get that far, it is on for approx 2 seconds then off, back on 2 secs, back off.. I'm going to try with mates PSU and see if it does the same

Weird, usually that's a sign of dead rams, but PSU is possible too.

Yeah at this point I'd try a known working PSU. If that's not it, then it's probably dead mobo or CPU.

This only happened to me before when the power switch got stuck. The switch, literally, not the button.

I would place a small amount of money on your cpu dying given what you've said.

I ran a test on the Power supply by shorting out the Green and Black Cable (http://aphnetworks.com/tutorials/psu_paperclip_trick), this lets the Power supply run without it being attached to the MoBo, it worked fine which kind of makes me think its the Board itself, haven't tested it with another Power supply yet though, was too busy this weekend.

Will let you know what it was when I suss it out...

It's possible there's a short between the motherboard and the case, or merely a dodgy power switch.

The second is easier to test, just put a jumper across where the power switch connects to the motherboard, for the first try taking out the motherboard and running it on the table.

also remove the cpu and ram etc and try booting the board.

if you get bios beeps, it's probably something plugged into it that's dead, add stuff until it works.

It was the Motherboard, just got a new one and I'm back up and running...