The following is a list of PC problems that often are power supply-related:
1)Any power-on or system startup failures or lockups.
2)Spontaneous rebooting or intermittent lockups during normal operation.
3)Intermittent parity check or other memory type errors.
4)Hard disk and fan simultaneously fail to spin (no +12v).
5)Overheating due to fan failure.
6)Small brownouts cause the system to reset.
7)Electric shocks felt on the system case or connectors.
8)Slight static discharges disrupt system operation.
In fact, just about any intermittent system problem can be caused by the power supply. Of course, the following fairly obvious symptoms point right to the power supply as a possible cause:->>
/*But obvious reasons, huh!!!*/
A]System is completely dead (no fan, no cursor)
B]Smoke
C]Blown circuit breakers
Source