It's not the 256MiB of memory, 600MHz core clock, 800MHz RAM clock, 128-bit memory interface or the fact that it can act as a Crossfire slave card that makes this card special. Nope, it's the combination of PCB layout and cooling solution.
The Extreme AX1300Pro Silent graphics card uses ReverseCool technology, something we recall seeing not too long ago. The idea is to take the major components of the graphics card and put them on the other side of the PCB. This allows the cooling to be on that side too, and given that airflow around the CPU region of the system tends to be good, ASUS can get away with a silent cooling solution.
Regardless of how well it cools, it looks pretty slick.
We expect silent PC fans (as in the people, not the rotary air moving devices) will seek out such a card for a system that needs decent, but not insanely fast graphics performance.
HEXUS.links
HEXUS.pr :: ASUS's press release.