Head on over to the AMD Overclocking Forum
and post up your system specs, primarily ...
Your limiting factor is your CPU multiplier, but you should easily be capable of a 240- to 250MHz system clock with your RAMs at spec speed:
With DDR3 1600MHz -- 13.5x240MHz, or 3.2GHz
With DDR3 1333MHz -- 13.5x250MHz, or 3.38GHz
Depending upon your motherboard, and your willingness to run something other than spec RAM speeds, 3.5GHz+ would not be out of the question with good air (and disabling the 2 weakest cores).
Either way you go, you should have no problems running the fastest of today's video cards.