. There are 2 general possibilities.
1) The CPU cooler (heatsink+fan) is not properly seated and the BIOS is detecting an over-temp condition and turning off the power supply. Carefully reseat the cooler to test it.
2) Your power supply has detected a short in one of its outputs and is doing an emergency power-off to avoid any system damage. To determine what is causing the problem remove all components, one-by-one, untill the power supply does not turn itself off. Of course, the system may not be able to boot or even the BIOS to start running (depending on what has been removed), but you should be able to locate the bad component. Do NOT remove the fans cables ! You need it/them to indicate when the power is not being shut off.Pieces-parts to remove (one-by-one):
RAM modules (if more than one, then one-by-one)
Hard drive power & data cable
Optical drive power & data cable
Floppy drive power & data cable
All other plug-in cards (one-by-one) such as a wireless adapter.
Fans (one must be connected at all times so you can see if it spins or not)
If the fans stiil are being turned off it could only be 3 devices that could be causing the short:
1) The motherboard - I have come across motherboards that have shorted themselves to death (all by themself).
2) The power supply itself.
Al the components can be tested by putting them in another "known working" system. The motherboard can't really be tested, but if nothing but the power supply and the fans are attached to it and the fans are still shutting off, then it MUST be the motherboard.
Edited by WinCrazy, 29 August 2007 - 07:07 PM.