Weird PSU Noise

[Locke]

Searched forums and didn't see anyone else with this bizarre issue .. so posting.

Lately my PSU (In Sig) has been making a weird humming noise. It starts whenever it's switched on for a few secs, stops, then starts again, repeatedly..

Definitely originates from the PSU because if I press against it, it lowers the noise but that doesn't stop it as I can still feel it vibrate along with the slight noise.

Any ideas?

 

[Locke]

Ok thanks for the suggestions, will try those now.

Already tightened the screws on the back though.