Can you attach a copy of the bios here so I can take a quick peak at it, I've never had a problem editing video bios and reflashing them before, it sounds kind of strange that the one setting took and the other one not.
Are you using the most current version of NiBiTor?
The new GT beats the old 640 and 320 meg versions of the GTS and does almost as well as the GTX in some games and a little worse in others. For the cash, the GT is about the best value if you can get one at or near their MSRP. The new 512 meg GTS does slightly better than the new GT but there you'll...
The 8800GT are about as long as a standard ATX MoBo is deep and I believe the ATi HD 3800 series are about the same size. About the only ones I know that have extreme size issues are the 8800GTX versions, they are super long. This is a shot of a 8800GT installed, it comes almost to the outside edge ...
If you plan on sticking to your budget, pretty much anyone one of the HD 3850 will do the trick for you.........They have about the bang for your buck in their price class right now. To bd the 256mb 8800GT are so much higher priced, it would have been a better pick.
If you can hold out and shop around, the 8800GT will be coming back in stock and at their MSRP as well. I picked my BFG 8800GT OC for a low price of $250 about 2 weeks ago and its one sweet card.