HD5970 pretty much pwns the GTX by a huge margin.
Synthetic benchmarks don't mean shit when it comes to comparing
GPU scores.
What matters more is real world performance in games,
efficiency, power consumption, heat, noise, etc.
A HD5850 either performs better or on par with a GTX470.
A HD5870 does not perform as well as a GTX480 but a slight
OC to the HD5870 will see it matching GTX480 performance or
exceeding.
The HD5870 beats the GTX480 in average frame rates, but the GTX
480 has MUCH better minimum frame rates (Like, 20 more minimum FPS
for a given game), which is more noticeable in heavily tessellated
games
