"The problem with the 590 is that its very loud and gets very very hot, since its basically 2 cards in one casing. As for it being on par with 7970, thats because you're comparing 2 cards in sli to one card on its own essentially. "
This is very situational, my friend has the Gainward one which is quite loud, I have the Asus one, its quiet as a mouse, I have your vision about AMD cards, loud and like jet engines, its just situational, sometimes they are louder, sometimes they are not.