|There was no reason to reset the BIOS. Hopefully you know your way around the settings & can correct everything later? Simply clicking "load defaults" is not the way to go if you want best performance.|
Anyhow, if you made no other changes, the problem is the card. Either it's defective, not fully seated in it's slot, or your power supply can't handle the added load of a gaming card. The 9800GT requires a power supply of at least 400W with 26A or more on the +12v rail. Most of them also require a 6-pin PCIe plug connected to the rear of the card.