My grandmother recently called me to her house with complaints that her computer will not start. Upon inspection I see that the standby light will come on when the PSU is turned on but when I attempt to power the whole computer (using both the external button and the internal mobo button) a flash will occur but then power off. I belive the standby light indicates that the mobo is recieving power from the psu, but beyond that I am not sure what could cause this problem. My apologies if this is a simple solution to this problem.