Don't mean to be argumentative or cause a dust up but I think the 7790 is spec out at about 85W, yet ASUS says their card needs 150W? Not sure what gives here, I don't see any major power change on this ASUS card that would need that much more power. AMD and a write up here at Tom's says 85W on the 7790 with a 450W PS needed.
I have ran across this before at the ASUS site on card power draw, not sure why.