I don't know how much research you have done into this, so here goes.
All 8800GTS's are actually produced by nvidia, and then the companies buy that and sell it under there brand name with extras. Also certain companies will pay more for higher binned versions which can get higher clock frequencies. These include BFG, OCZ and XFX.
Now on the overclocking side of things, many forums have had people overclock them. There are guides out there, as well as guides to voltmods. I am not sure if i can like to them, so i will anyway. If i mod doesn't like it, just edit my post, or tell me to do so
Anyways, this is a link to the voltmods. Do this at your own will. Void warentees etc.
Linky
And on overall overclocking results, check this one out. Some may be done with voltmods, so check through them to find out which ones are and are not.
Linky
Now just as a note, this was all found via simple google searches, so maybe you should look around before hand. More technical questions i can understand, along with if you are opening a thread to list results. For example ur 3dmark05 hwbot thread. Hope this helps!
welcome to the dev
- Paul