The GPU is overclocked from 575MHz to 626MHz and the card also has 2000MHz memory, which is 200MB more than standard 8800 GTX graphics cards.
It runs stable at 626MHz but overclockers will be able to get it much further.
A chap called Vince Lucido set the 3DMark 2006 world record at over 24,000 points with a pair of EVGA 8800GTXes and an EVGA 680i motherboard, so anything is possible.