I take it that the C partition that you formatted is the boot (OS) partition? If so, then you basically reinstalled Windows when you installed the new graphics card, so there shouldn't be any conflicts with leftover driver files, right? That's what I would have done, too, if my previous card had been an nVidia model. It wouldn't have been necessary had your previous card also been an ATI model.
Have you gotten any BSODs (Blue Screens Of Death)?
Have you checked the new card's operating temperature?
Have you tried re-seating the card after clearing the PCIe slot of any dust?
"They should rename the team to the Washington Government Sucks. Put Obama on the helmet. Line the entire walls of the stadium with the actual text of the ACA.
Fix their home team score on the board to the debt clock, they can win every game 17,000,000,000,000 to 24. Losing team gets taxed by the IRS 100%, then droned."