^^ /facepalm.
http://hexus.net/tech/reviews/graphics/36509-nvidia-geforce-gtx-680-2gb-graphics-card/?page=16
'Bang4watt' and efficiency scores, GTX 680 rules all. I wouldnt want a 7850 for 'power consumption' because despite using a little less power, it doesnt perform anywhere near as well per watt.
You maybe put two 7850s together in crossfire and come close to or even match the GTX 680 performance, but then you are going to end up using even more power for the same or less performance.
This is the first generation in a long time that I prefer a single high end card (either GTX 680 or 7970) to two mid range cards (dual 7850 or GTX 560 / 570). The single high end cards are simply better in every way.
My GTX 560 tis on the other hand were absolute beasts when the released, close to GTX 480 / 570 performance at the time when overclocked, far far less power consumption. Two of them cost less at first and outperformed a single GTX 580.
Price / Performance, and Watt / Performance is what you look at, not just power consumption alone.
if buying a card right now I'd be getting that VTX dual fan 7970, but I'm going to skip this gen and wait for the 28 nm tock generation next year.