Whitch verion of CCC do you have?
To unlock the ATI Overdrive in CCC you have to click the key button.. then you should be able to change the clocks manually.
I'd try reinstalling the drivers... had some few issues with the CCC and drivers myself the first time I installed them.. reinstalled them and everything worked nicely.. if the version you're using is one of the newest once you might want to try 8.11 or 8.12
To unlock the ATI Overdrive in CCC you have to click the key button.. then you should be able to change the clocks manually.
I'd try reinstalling the drivers... had some few issues with the CCC and drivers myself the first time I installed them.. reinstalled them and everything worked nicely.. if the version you're using is one of the newest once you might want to try 8.11 or 8.12