Ehh even though you don't think that the 9600GT would draw enough power to strain the psu i'd say try it anyway.
Also, probably the easiest thing, if you wanna try to figure out if it's your gpu fan, try manual setting your fan speed to various other speeds. I find with my iceq4+ that at certain settings it makes a high pitch sound but at others it doesn't. This isn't a full proof test because if it's a general fan problem, it wouldnt show up, but it's something to try
Is a electro mechanical noise.First make shure it did not came from the heat pipes in the card.
Then in a car supply store buy a high temperature silicon (the one used in motor engines) and fill the air space in the power coils you can find.
A high quality power supply should not picht any sound. If have warranty, use it.
Ok so i plugged the 9600gt in and its making the same noise, i'm pretty sure it's the power supply but it's hard to hear as the 9600gt makes a lot of noise. Im going to move the PSU out as far away from the case to try and isolate the noise so I'm 100%.
Ok for anyone else interested. I found out that the menu of the game and the game i was playing to test, STALKER CALL OF PRIPYAT was generating extremely high framrates.
As High as 2500FPS on the menus which caused the resonance and coil whine. I simply forced vsyync on and fixed the issue. The reason it took me longer to find out was that VSYNC was locked on the game but mustn't have worked.
Apparently exceptionally high framerates such as 1k plus can cause the coils in the psu to resonate and generate exceptionally loud coil whine, sometimes with a particular motherboard and GPU combo. It was definitely the PSU causing it.
When the framerate is below a couple of hundred or less there is little or no coil whine from the PSU.