Yesterday while in use my PC suddenly shut off, at first I though it was the electric but nothing else went off when I tried to turn it back on it powered up for a sec then went off about a second later. I made sure all connections are solid , tested ram, nothing then I read a guide and cleaned the dust from my PSU, after reassembling it turned on, wood for about 2 hours then the same thing. turns on, goes back off seconds later. I left it and now enter I run it on fans run, mouse led lights up but n beeps or signal to keyboard or monitor. is this definitely my power supply? any help would be appreciated.
heatsink sits ontop of the cpu with thermal paste between it and the cpu.
the fan sits on top of the heatsink. the heatsink fins can get blocked with dist and fluff gets under the fan so you need to disconnect and lift off the fan with out removing the heatsink from the cpu.