Gaming graphics card needed

Looks like that is this mobo: MSI 760GM-P23 (FX) which is AM3+ with 1x PCIEx16 slot.
That can take a fair amount of cards (prvided your PSU and case can handle it). However top of the line cards may be overkill depending on your CPU and RAM.

As okalandmurphy said, what are your other specs? What games do you plan to play? How many watts is your PSU? Then someone can make a better recommendation.