Just of note, for mining those cards are terrible MHash/$. If you are getting them for gaming though, more power to ya.
can you explain why? just currious...
the 6850 is $80 more expensive than a normal double slot one.
the 6990 is $170 more expensive than a normal one. (though it is a watercooled unit, which is worth something).
I was hoping for a more "technical" reason... What are the expected hashing rates of the water-cooled 6990 vs. double-slot 6990?