I'm running a batch of 8Gb 470/480/570/580. All running at REF 30 now and getting an average of 150 - 200h/s extra a card on CN-Conceal. These are all non-bios modded. Extra H/s bonus for setting tRFC (155) & tRC (69) across all. All around 1750 - 1800h/s a card. Haven't started playing with the straps yet. Hope this helps someone starting out.