While it's true that 7970CF wins some benchmarks, about every review on the planet says the 680>7970, 680SLi >7970CF, and 690>7970CF.
Look what else Anandtech said about 7970CF:
http://www.anandtech.com/show/5805/nvidia-geforce-gtx-690-review-ultra-expensive-ultra-rare-ultra-fast/19...