System high pitched squeal

I seem to get this high pitched squeal from my PC. It's only audible when processing on my pc, not a screaming sound but more like a cheap dog whistle, I.E. converting photos to jpeg. And my speakers go hay wire (with or without processing)! I am trying to figure this one out and may need some help.

THINGS I HAVE TRIED:
"process of cancellation" hard drives, sound card, speakers wireless card.
I have plugged my speakers to another source, they work fine.

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I have heard that this might be my PSU, it's a generic 350w PSU. I do not want to take the effort to change it out unless I can confirm that this is very likely to be the culprit.
I have had this set up for some time with out problems, until about a month ago.

its the cheap PSU. i have had the same problem before. cheap PSU will poor "earthing" and working at their peak will submit those annoying buzz at the background and the annoying current noise from the speaker.

try swap a PSU.