|If the fan is pushing air and not making any strange noise, it's fine. Download SpeedFan to monitor your system temperatures as the PC runs. |
However I doubt that heat is your problem, since the computer needs time to recover before it can be powered on again. Last time a computer did this, I had to replace a bad voltage regulator on the motherboard. But before your blame your motherboard, test the power supply. If you don't have a spare power supply with the same (or greater) wattage on hand, find a local computer repair shop; they usually keep plenty of spare components. The nicer shops will let you use spares free of charge.
Now fully Se7ened.