Tested it in my friend's old computer and no luck, there was a hum. (The power switch was not plugged in and we tested several different spots on his mobo for the switch cable, however we may have missed the right one)
I used both a surge protector and a standard outlet.
It is a Corsair CX500 ATX Power Supply
Intel i5-2300 LGA1155 2.8GHz Quad Core Sandy Bridge
4GB Corsair DDR3 1133 RAM
1TB Western Digital 7200RPM SATA 3.0 HDD
nVidia GTS 450
EDIT: It was an incredibly quiet hum, as in almost inaudible for both me and my friend.
Edited by sausage, 28 July 2011 - 07:15 PM.
If I'm posting, I probably have something horribly wrong with my computer, there's no obvious explanation for it, that's just the way it is.