I'm hoping those cards OC to hell and back like the 500's do. At 900Mhz for both the 570 and the 580 they are in their own leagues and seems a bunch hit those freq. My poor 470 only hits 875Mhz max, 850Mhz 24/7 and I barely swipe past a stock 480 ( ). If those 6900's they can do a good 1100mhz probably without that PowerTune thing on, I bet you they'll be beasts. I just hope most of it can be done on the stock cooler or a decent waterblock.