Been playing a loooot of borderlands 2 lately, and gonna play the batman arkham series of games since I got em on steam sale, and I wanna replay mirrors edge, all of which have support of gpu physx. I have a 7950 right now, in my asrock extreme 4 gen 3 mobo with a 2500k for the cpu so my pcie slots are all running at 2.0 speeds. I've got an old evga 460 ftw laying around and s 750W 80+ bronze psu, would putting my 460 in the second pcie 2.0 slot for a physx card reduce preformance of the 7950? My mobo's manual says that the pcie slots run at x8 instead of 16 when there is a gpu in both of them so I'm a bit weary since I don't know if a 7950(at 1000 mhz) uses more bandwidth than x8 can provide.
A 2500k will run physx fine on borderlands 2 without useing a dedicated physx card.
Haveing a dedicated physx card can bottleneck higher cards if the physx card is too low.
Here is some dedicated physx card testing http://youtu.be/cbww3dhzK0M
But i am not so shure it carys over if you are useing hybrid physx (amd with nivda)
Hybrid PhysX: http://physxinfo.com/wiki/Hybrid_PhysX
Just buy the cheapest geforce card w/ physx and has been tested successful with 4 and 5 series geforce.