Not a very big jump. about 3% on a good day. There is some user here (don't quite remember his name but it starts with B) with a monstrous Gigabyte HD7950 @ 1280 MHz beating alot of HD7970s max overclocks. The 7970 needs about 1250 MHz+ to beat that card .
Edited by HeadlessKnight - 9/16/12 at 7:00am