Ugh... over clocking the video card? Good ol' ATI tools 64 bit version, and Riva Tuner 64 should do it.
Just be sure to get the newest ones. NVidia has been releasing drivers that are somewhat compatible with em' now a days.
For instance, when I over clock my cards using the newest drivers, I get worse performance, hehe!
I think there is another ATI utility that does well, but I am not familiar with it.
--Lupi