Try Riva Tuner. Tool release for ATI card. I used it on my 9600 (ancient relic), basically ***** proof which is good for me as I know next to nothing. It allows you to raise the rates independently and then test it, allows you to revert if you are not too happy, etc. Go give it a try.
Riva is by far the best out there i reckon so easy to use plus if your lucky you can unlock some hidden stuff on your card hehehe ie. pipelines its awesome, have a play... you'll love it