[citation][nom]scook9[/nom]By putting both gpus on one board you eliminate ALOT of redundant circuitry which helps them maintain the lower than you would expect power envelope without having to downclock too severely. I think it will be a safe bet that this will both out perform and out cost the 6990Jury is out on noise and heat until some review get up[/citation]
You say this, however the 6990 is closer in power consumption to two 6950s than two 6970s, and this is right where it performs. Let's remember that the 5970 (294W TDP), which was in essence two 5870s at 5850 speed on one board, used about the same or slightly less than two 5850s (2x151W TDP). If you take a look at these figures in
Anandtech's 580 review, there's no difference at all, meaning that the small number of extra ROPs and shaders is taking away the savings gained from having the one card. The difference between a 5850 and 5870 is 33W in this test but let's remember the clock difference is 17% and the 5870 is using only 12% more juice, so not much can really be going to the unlocked hardware. Note that the 580 uses more power than the 5970 under Crysis - and if the 6990 uses another 113W on top of that, how much will the 590 use when even the 580 is using more power than the 5970?
I'm really looking forward to seeing what nVidia can pull out of the bag.