>PhysX has been added to the PC version of Batman with the v1.1 update. It does not ship with PhysX settings out of the box. Once installed you are provided several options for PhysX – Off, Normal, or High with various card recommendations.
The nVidia drivers allow you to change the PhysX settings – turning optimization on or off as well as the ability to choose which card handles the PhysX acceleration. I had thought offloading PhysX from my 2 x 285GTX2G cards working in SLi to the built-in 980a/780a would make things faster:
However, after applying the v1.1 w/ patch PhysX Batman, Normal PhysX was enabled. I was suddenly getting very low framerates (15fps). I turned on the “Show SLI Indicators” in the 3D settings menu so I could see how hard each of the video cards were working. They were both very low, indicating the cards were not working up to their ability, yet things were still slow. CPU usage hadn’t spiked high enough to be a bottleneck and memory was free and clear.
It appeared having the PhysX on the older (and slower) chipset was slowing everything down. To test the theory I turned off PhysX and was getting framerates in the high 50s. It certainly was PhysX related.
I turned PhysX back on, normal setting and in the nVidia control panel I changed the setting to enable PhysX on the 285s instead of the 980a/780a. When I tried it again PhysX was visibily running, fallen leaves moving under your feet accompanied by smooth framerates between 55 to 60fps.
Based on this experience it appears that having PhysX enabled on an older chipsets may actually decrease performance over having PhysX enabled on the same video card(s) doing the graphics processing.