From neowin.net:
Asus has unveiled a new GeForce 6600 DDR2 graphics card with a twist. Typically, graphics cards have their processors on the topside of the card, and when fitted in a standard computer case have their GPU cooling solutions facing downward. We all know that heat rises, so naturally this is not optimal for cooling the GPU, as some heat is allowed to return.
To counter this, the Asus Extreme N6600TOP Silent graphics card has the GPU installed on the backside and fitted with a heat pipe. Asus is calling this new cooling method ReverseCool, and boasts that it allows for temperatures up to 30 degrees cooler while remaining completely silent, which could prove very attractive for gamers craving a near silent computing environment...
Although the card is listed in Asus's website, pricing and availability details were not available.
Makes sense to me.