Graphs above are interesting for a few reasons:
(1) shows clock-for-clock improvement in GTX680 vs. 580 as 2-5%. Thus it has triple the shaders but each one is about 1/3 as efficient.
(2) nVidia is going to clock this thing like crazy to set it apart from both the 580 and the 7970.
(3) AMD was f'ing with its customers by releasing a 7970 at 925MHz. It could easily have released one at 1GHz, but it didn't do so, because it will instead release a higher-priced card at 1100MHz or so. Maybe a 7990 for $600, slotting nicely just above the 680 in price?