Yeah, I'm going to get a 7770 Vapor-x which is the one I was thinking about buying in the first place. From now on, I'm going to avoid reference cards.
Coil whine has little to do with reference/non-reference. It's mostly related to component quality and construction quality; XFX is a solid OEM but even a few slip through their QA. Even getting knocked around hard enough during S&H could cause coil whine. Non-reference cards typically have different coolers and firmware but the VRMs don't differ by much.
If you're happy with the performance of your 7850 then I suggest that you contact XFX for an RMA, they have an amazing warranty service in North America