The base clock speeds on the GPU for this card come in at 750MHz. Not bad but the stock HD 5870 comes in at 850MHz, so there is work to be done to try and get the performance to that of a true dual HD 5870 setup with just a single card. When it came to overclocking the PowerColor LCS 5970 I was able to bump the speeds up from the as delivered 750MHz to 1010MHz, a 260MHz gain in clock speed. The memory clock speeds did not really show more than the air cooled reference version at 1250MHz, but still a 200MHz bump, or close to a 20% increase.