PSU not poweful enough?

I recently upgraded my main pc with a GTX 260 and a 1TB drive and now when I use Folding@Home x86 i hear a small sqeaking noise (kinda sounds like a homing beacon, lol). My current Specs are:

Core 2 Duo E6850
XFX GTX 260
3 Sata HDD
1 IDE DVD Drive
EVGA 680i SLI MB
Antec Neopower 500 watt

The real question is is the noise being caused by the strain of the extra components on the the PSU? The noise only happened once I upgraded. I am i doing damage possibly to the PSU? 500 watt is the minimum for the GTX 260 and I may be pushing it. It doesn't make noise when I use FAH GPU but only when I am using the CPU client and i haven't noticed it during games either.

EDIT:It sounds like chirping really. Just chirps like very second.