theres a really anoying high pitched noise coming from my pc, i think its from my psu, i recently got a new case and psu exactly the same as my old one, and my old one didnt make this type of noise!!!!
If you can isolate the fan that's causing the problem, you can either replace it or repair it. Usually a high squeal means the bearings are dry. There is a quick and easy way to add a few hundred hours life your your dying fan. Just peel up the sticker which seals the fans motor, pour a drop or two of lightweight machine oil (like sewing machine oil or 3-in-1), clean up excess oil with alcohol and replace the sticker. ...or you could just replace the fan
But do have in mind that once you hear weird noises from your fan, adding oil will in no means solve the problem, it will only postpone it until even oil can't quiet the fan down. However, if you regularly put oil even when new, it will make it last longer. I don't bother with it though as fans are very cheap and last a long time.