ive got a packered bell tower and the fan on the psu as stopped working.the psu thats in it at the moment is the origanal psu. model number fsp250-60gen. and the motherboard is p55800-vm/s. ive been looking at psus on 2 well knowed web sites ie p c world and m a p l i n s. i know it is 24pin psu.what i want to know is can i put a 500watt psu in ive been on google to look for the same model thats in it but most that ive read have replaced them with cosair or something like that and other models. there is a block coming from the psu 4 pin it as 2 yellow/black wires. and 2 black wires going to the motherboardso does that operate the fan if so could there be a problem with the motherboard. or is it the psu as nearly dead any advice please as im not sure what to get im not into gaming its just an old run of the mill xp(i know why have i not upgraded yet)im about to try and put windows 7 on a external usb 1tb harddrive seagate but thats another post once i get the psu sorted out any advice please on the psu thanks. kennyboy.