http://www.techpowerup.com/mobile/reviews/NVIDIA/GeForce_GTX_Titan/27.html
At 1200p you're looking at a 29% average advantage over the 7970GE and a 33% advantage over the GTX680. This improves slightly at 1600p to 31% and 42%. The bad thing is that's it, since you have almost no overclocking headroom.
It does go from 876 boost clock to around 1Ghz boost.
7970 can't actually beat it, but it does get close to it, at least for now.