[Yellowbeard]

Originally Posted by TAKTAK

i thnik what your are encountering is what is known as 'coil whine' OR 'coil hum', which is
but to pinpoint where the noise is coming from exactly, use a rolled up newspaper on your ear and use the other end like a stethascope (i.e. take the side panel off and listen to the various components)... (sounds weird but it works) and this will allow you to determine whether it is the PSU or another component that is whining.

Excellent advice and troubleshooting method!