it might work ok, for a short period. I ran a single 6850 from a 470w TR2 for a while, but different tr2's are made with different designs > see this article http://www.tomshardware.com/reviews/power-supply-oem-manufacturer,2913-9.html
. All their decent models are made by Channel Well, the others, particularly the RX series are known to not put out their rated power. The problem with taking this kind of chance is you could end up with not only a blown PSU, but when it does blow, it can put a voltage spike out that could blow your motherboard, video cards, ram, pci cards etc.......would I take that chance....no.