I hope so, last time I heard a noise like that it was a failing PSU but this one is definitely coming from the GTX 280.
I've got till Monday to RMA it so if it's got a fault I hope it shows itself soon.
I have exactly the same. At high FPS there's this horrible buzzing/squealing, I had it on my old 8800 but this is much much louder.
I understand it's just cheap capacitors or something along those lines.