PC turns off a second after turning it on

What are the system specs? It could potentially be incorrect or bad RAM. Could be a bad CPU or motherboard as well. I am just throwing out components that would cause an immediate shutdown.

I had a screw that shorted out my motherboard, and the PSU shut itself off. Maybe you have a short or grounding issue?

The front panel reset switch could be shorted, you could have something else plugged into the reset pins on the motherboard.... just throwing stuff out there.

I had the same problem and i was trying to shove a corsair 800watt gs in my 14x5x12 case and the same thing happened so i went it, wiggled some wires and i found out it was the sata cord running from my hdd to the motherboard andif it wasnt that i unpluged all the usb devices and it still starts fine

yeah its your psu(most likely)

test with this
http://www.youtube.com/watch?v=5FWXgQSokF4

if it passes then its your motherboard

CPU: AMD A4-5300 3.4GHz Dual-Core
MOTHERBOARD: ASRock FM2A75 Pro4 ATX FM2
RAM: GeIL Value PLUS 4GB (1 x 4GB) DDR3-1333
PSU: ATX 500W

thats not true in fact those will not have that effect if they are bad then there will be NO post but with a bad psu(granted it may also not post) it will go on then off

check you psu

Was this problem solved? Just put a system together with the same motherboard and have the same issue. Can't seem to figure out what the issue is.

Asrock Fm2a75 Pro4
Amd A8 5600k
Kingston hyperx 1333 4gb sticks

Power on the computer the fans spin up, cd rom starts to spin up and then it shuts off and will not restart untill the power supply has been cycled off then on again.
Doctor debug shows post codes up to 0x4f which is - DXE UPL is started.

Im currently swapping the psu with another to check for a power supply issue.

yeah im almost possitive it is... and no the OP never responded or picked a best answer... keep us posted on how the new PSU works

sorry for the late reply, but I got it working about a month ago, It was actually an issue with a connection not being fitted properly; so nothing to do with the PSU.

Thanks for the responses though

ok glad i could help(kinda) anyways dont forget to pick a best answer