The GTX 780 has been overclocked, and has set a world record for single-GPU performance.
A team of overclockers from HKEPC -- Mad222, Stephen Yeong, John Lam, and Mr. Wong -- have set a world record for overclocking the GTX 780 graphics card. Using liquid nitrogen, they have managed to get the card to outperform even the dual-GPU Radeon HD 7990, using the single-chip GTX 780.
The clock speed they have achieved is 1855.2 MHz GPU; they got the memory running at an effective speed of 7.4 GHz. At these speeds the card scored a grand total of 41,180 points in the 3DMark Cloud Gate benchmark, which is a very, very respectable number, and according to other sources, even a world record for single GPU performance. For comparison, the GTX Titan scores about 27,000 points stock, and the Radeon HD 7990 scores around 32,000 points, all with a degree of variation depending on the configuration used.
The CPU used for the benchmark was an Intel Core i7-3960X, which was clocked at 5.5 GHz.