Re: PSU fan suddenly loud...
The PSU fan should just automatically work. There's nothing to hook up. If that stopped working I wouldnt use the comp at all until you get a replacement PSU. Overheating a PSU could be dangerous. So i would just replace the PSU, maybe even get more wattage than the last one, the fan issue could have been caused by the orig PSU overheating due to being overworked.