We've already been hands-on with NVIDIA's first Kepler GPU, but all those fancy features count for nuthin' if the benchmarks don't back them up. So do they? Huh? Do they? NVIDIA told us to expect a 10 to 40 percent performance boost from the $499 GTX 680, versus AMD's pricier Radeon HD 7970, and it appears that was no exaggeration.