ATIccelerator II can change ATI graphics cards frequencies live, on-the-fly, under Mac OS X.

Graphics cards overclocking on the Mac finally comes out of stone age!

WARNING
ATIccelerator II comes with ABSOLUTELY NO WARRANTY. If you destroy your costly 9800 Pro or your now worthless Rage 128 because of a bug in this program or your careless utilisation of it, you're on your own!