I dunno why nvidia would reccomend against AS in general, but I used AS3 on my gainward to attach a crystal orb and everything's been peachy... the pins clamp the hsf down nice and tight and I got a 25mhz boost to the 235/520 oc I reach with stock... I guess the only worry is to make sure that the heatsink stays as tight as possible against the gpu... if you don't have pins on your original hs/f and nowhere to stick pins into the pcb (prolly thermal expoxied on in this case) then you need to use arctic silver/alumina adhesive. One point when applying any AS product is to be really neat cuz I know a few people who phucked up their cards when some excess AS2 or 3 shorted out some pins on the RAM... could happen to the gpu too I suppose... Just do everything carefully and everything should be fine...