They are very hard to find, but see if you can get your hands on a Saphire Toxic 6950. There's a little switch on the card that clocks it to 6970 speeds, and it can be overclocked well over that as well. I run 2 of these in crossfire and both cards run about 10% faster than a 6970.
---------- Post added 2011-12-28 at 09:46 PM ----------
550 for a 7970. I'll let you guys around these parts know how they bench when mine arrive on Monday.