Did you install the card yourself or did someone do it for you? If someone did it for you they probably checked the bios settings already. I assumed that you had installed the card yourself, but since you're not sure about the bios that's probably not the case.
You can find older drivers at
www.guru3d.com or
www.driverguide.com But only go for the official ones for now rather than the beta tests, because many of those are to work around certain problems with certain games and cards.
Some games are programmed to run better on certain types of cards. Some will play better on Nvidia, some on ATI. Drivers will make a big difference between games too, one driver will run SimCity 4 awesomely, but won't play nice with TS2 and causes red water or artifacts. Another will screw up Civ IV but works fantastic with Sims 2.