Yup, this game has come leaps and bounds from where it started. GTX 580 1.5gb currently running the latest Official Release.
My system is in my stats, and with a Frame Limiter at 60FPS, the games runs AMAZING on Ultra, i just edit the particles down a bit because on that setting Fog and Smoke (especially during the Intro scene) cause some huge FPS hits, especially with AA Enabled. Besides that, 60 FPS everywhere, even in cities now *yay!* fluctuates to 58-59 when loading stuff (i can handle that!)
Have fun with your nVidia, I was an AMD user of a 5770 before my switch. Not going back to AMD anytime soon, not their GPU's anyway...
