Sapphire HD 7870 Review @ OCC
 

Overclocking this card was fairly easy. With a stock clock of already 50MHz over the 1GHz mark, I wasn't expecting the card to have much headroom for overclocking in the first place. However, I was able to achieve an overclock of over 200MHz for the core clock. This resulted in a final clock speed of 1257MHz. As for the memory I was able to bring it up to 1331MHz, not too bad for a video card!

http://www.overclockersclub.com/revi...phire_hd_7870/