Weird PC Noise issue

Hey all. 

I'm trying to figure out the cause of a noise that is coming through the signal line on my PC. It is an Acer Aspire M3470G-UW10P desktop with a  AMD A6 3620 / 2.2 GHz CPU  and  AMD Radeon HD 6530D onboard video. It's connected to a Behringer MC202HD USB interface. The noise is equally present when using the built-in computer audio, the Behringer interface, or headphones connected to the computer's headphone jack. Here's a volume-boosted recording of the audio:    (Click play after you get to the link)

This is my main studio PC and I use it for recording. (or at least I would if it wasn't making this racket.) 

I hate to buy another PC, because who's to say it wouldn't make noise too? 

I would be eternally grateful if anyone knows what's causing this noise and how to get rid of it. Thanks much!  - Bob.    :-)