I have a XFX 5850 and it will only go to 775MHz core. Looks like I would have to reflash BIOS. Was hoping I wouldn't have to. If I flash the 5870 BIOS to my card are there any benefits other than giving me a higher clock setting? Like say if I wanted to use the card for gaming or something a few months from now. Would it effect it's performance at all?
Take care to make sure the BIOS you are flashing is compatible with your card. Many XFX are not reference boards and have different voltage regulators on the board.
It might be safer to use RBE to get the BIOS from your card and edit the overclocking limits yourself, then flash the edited BIOS back onto the card.