I have an HP desktop computer sitting here that keeps shutting off by itself 30 seconds after I turn it on. I tried changing the PSU, re-applying thermal compound, and taking some of the ram sticks out to see if its the problem. None of the above have solved it. They computer keeps shutting off.
There is an exception to this however, and that is that it only shuts off if I start booting up Windows Vista from the HDD. As soon as I boot from the HDD it shuts off after a couple seconds. I tried booting something from a CD and it stays on with no problem.
I downloaded the Western Digital diagnostics tool and ran a QUICK TEST only. It said no errors. Does anyone know what might be the problem here? I need to fix this ASAP as its the main computer for a business.