You do realize that if there are components still overheating in the powersupply and that temperature is a significant cause of power supply component failure and even cause incorrect voltages to be outputted; its not just as simple as preventing it from completely overheating and shutting off. The damage to the power supply could already be done, there could also be damage to other components. You should also make sure you have a quality power supply of sufficient wattage. Also, if you have fan blowing into the back of the computer then you are reversing the airflow; the power supply fan generally blows out and any case fans and some video card cooling systems generally also do a front to back airflow.