In the more intensive SunShafts test run of the benchmark, the pair of NVIDA GeForce GTX 680 cards were only beaten by the Radeon pair by a thin margin of slightly over 4% - this is at the resolution of 2560 x 1600 pixels with anti-aliasing set at 4x. For the rest of the benchmark, the Kepler pair managed to stay well ahead of the AMD camp.
In terms of scaling performance for the Kepler GPU, with reference to the SunShaft runs at its highest resolution, both sets of cards from NVIDIA and AMD scale in rather similar proportions. The pair of AMD Radeon HD 7970 cards scaled in the range of 16.4% to 65.2% while the pair of GeForce GTX 680 scaled in the range of 18.1% to almost 54%.
From the performance logs, it appears that GPU Boost kept both GPUs on the GeForce GTX 680 SLI setup at near their maximum core clock speeds of 1110MHz during the load periods of the benchmark test.