I just recently bought Batman Arkham City. It runs very well apart from the well known DX11 problems. I kept PhysX on high.
Was just looking through the Nvidia panel and it says you can change the PhysX to run on either GPU or CPU, or leave it on auto.
Is there any point in changing this? Maybe better to put second card on dedicated? Or does this mean it won't run in SLI if I do that?
you have 2 580's..... you can run it straight off the cards with no problems. Lesser cards you might think about running it off the processor. with processor intensive games you might think otherwise, but again, you have more processor than you need......... leave it on auto.