I just reinstalled Fedora 18 on my notebook with dedicated card.
After fresh install:
1. set power profile to low (because of the fans) -> totally laggy Gnome3
2. added radeon.pcie_gen2=1 to the kernel commandline -> no lags with Gnome3
Code:default engine clock: 680000 kHz current engine clock: 99990 kHz default memory clock: 900000 kHz current memory clock: 150000 kHz voltage: 900 mV