I am having trouble with computer hanging up and it happens after start up...things can be running for a while but then a noise...sort of a soft grinding, but not really abrasive grinding if you get my drift, comes from the power supply. The fan is running smothly and doesn't change during the noise. i have isolated the noise to the supply. Hav e stoped the CPU cooling fan for example. Am I in need of a new power supply. Seems a weird thing to fail. No? could there be any relation to hard drive problems or is the noise a pretty determining factor that something is a miss with the power supply?