A couple things can work:
1. If it makes the whine at idle, it's because of the core clock speed and the voltage. Try running a game and see if the whine goes away, if it does, just tweak the idle clocks if that bugs you enough.
2. If it still whines while gaming, it could be because it is trying to send frames too quickly (too many fps) and I know this sounds like bullcrap, but it isn't. I've got a 980 that runs certain games way above 60 fps. After noticing the whine on my card, I set the fps target to 60 (this lets it fluctuate as long as it hits 60 at least) or you can cap it at 60 (which means it can't go above that number at all) and the whine stopped.
3. Is it running hot? How are the fans? Are the voltages optimized? look for small things to test to see if it changes anything.