Performing a firmware upgrade to the 7950 will only mess up your card. The firmware upgrade will not work. You best bet will be to OC the card to get better performance. Though RivaTuner is good Coolbits is better. Basicly the 2 are the same and unlock hidden OC abilities that are already in the nvidia display drivers.
Hmm i agree. You are much safer OC with programs like mpilchfamily said.
But if you chose to go with bios flashes here is a site that has a lot of bios files available for different chips. Good luck.
http://www.mvktech.net/component/option,com_remository/Itemid,26/func,selectfolder/cat,4/