"There are a few utilities available for overclocking graphics cards out on the web that for the most part work with most video cards. Many of the top manufacturers have their own utility and Sapphire is no different with its TRIXX utility. I have used this utility before and it is fairly straight forward to use. Sapphire has equipped the Flex with a Vapor Chamber-based cooling solution that allowed temperatures to hover around the 60 degrees Celsius mark when the fan was spooled up to 100%. This level of cooling let the HD 6950 Cayman core run up to 904MHz, or 104MHz over the baseline setting — this without the ability to increase the voltage on this card. The Hynix GDDR5 memory was able to scale another 255MHz over the as-delivered 1250MHz clock speed."
Any major computer upgrade generally requires a full software reinstall too. No so if you heed the advice in the guide to Upgrading a Motherboard without Reinstalling. PCSTATS Tips