Today for overclocking we are using the Catalyst Control Center.
We pushed the core to 1,180mhz, translating to a 12.3% core clock increase. Memory could be pushed to 1,360mhz (5.4Gbps effective), translating to a 13.3% increase. Both are healthy final results.
The overclock pushes the card to a new performance level, 300 points behind the reference clocked HD7970. Well worth the effort!