Performance of an ATi Radeon HD7970 over a GTX580 in a Nutshell:
In average 10% more FPS. Not many FPS in Starcraft 2 or GTAIV, but 25%-33% more FPS in Serious Sam BFE and Crysis 2 with SSAA. Increased Tesselationperformance.
Powerdraw: 185Watts under power, 12Watts idling.
Fan: idle 0.7 Sone, power 4.1 Sone (AMD Fandesign, Custom ones can and will be more Silent)
http://www.pcgameshardware.de/aid,86...fikkarte/Test/