overclocking influence on 8800 gts ?

Depends on how you overclock it, in my experience with nvidia cards you can OC the core about 100mhz and the ram about 75 mhz safely without better cooling

of course this always varies, but thats a pretty safe OC. If you want to OC more then youll have to do some testing (get load temps etc.)

if you want to do that check the safe ranges for temperatures on your card and test from there