Overclock them a little in the performance tab in CCC
Then search for Profiles.xml and open the one in the ATI folder if you have several (for me it is in C:\Users\Meh\Appdata\ATI\ACE) then see next points below copied from
http://forums.eagle.ru/showthread.php?t=68060 (Check out all suggestions in this forum)
• Disable CATALYST A.I - You must follow instructions below to disable Cat A.I. The slider settings are for enabled only, they've made it harder to disable it but here is how with latest drivers:
* Close down CCC.exe and MOM.exe via Taskmanager
* Navigate to <username> \AppData\Local\ATI\ACE\Profiles
* Open Profiles.xml with Notepad
* Alt + F and search for "Catalyst"
* Change Value Enable to Disable for Catalyst A.I
* Save
* Restart
In that file you can also search for the line below and set to enable, so:
<Feature name="ForceHigh3DClocks">
<Property name="ForceHigh3DClocks" value="Enable" />
</Feature>
This should hopefully make em run at full clock if you overclocked them in CCC.
p.s. I use the 11.4 WHQL certified catalyst drivers from guru3d (browse these forums for the link if you feel like upgrading)