Hi d-a-l im jus wondering how to check my power supply, becuz i think it might be why my computer has been restarted after many hours on the computer..

Without specialty electrical tools there is not much you can do.

A basic test is just to try another PSU.

PSU issues usually show up at start-up unless it is overheating.

Have you checked the fan/s? Cleaned the unit?

i took a look at the fans and i seen alot of dust which i tryed ot clean out.. how would i check the heta in the power supply?