GeForce GTX 680 Can Be Flashed to GTX 770?@ 2013/05/14
A Reddit user claims that a simple BIOS flash of the GeForce GTX 680 could turn it into a GeForce GTX 770. The BIOS ROM image, which probably works with reference-design GTX 680 boards was posted, along with a GPU-Z screenshot of a "GeForce GTX 770" obtained this way. The BIOS runs the card at 1059 MHz core, 1125 MHz maximum GPU Boost, and 1752 MHz (7.00 GHz GDDR5-effective) memory, yielding a memory bandwidth of 224 GB/s. The BIOS file can be found here (try it at your own risk).