Sure its coil whine and not the fan? If it drives you crazy and its still under warranty send it back.
I'm trying to find a way to kill the GPU fans altogether to test that, but I havn't found a way yet. Do you know of one?
EDIT: Unplugged fans. Noise is still happening.
Use your finger to stop the northbridge (small fan on mobo) fan when the whine kicks in. It may be electrical noise associated with that.
The area around the PCI slots was hit by the head of my modular cooling unit (It swung down, I had it resting atop the case and forgot about it). Could that have done it? This is an armored/protected board, and you can't even see any evidence of the hit on the protective shell/etc itself.