I doubt it very much,they are two different cards.One runs DX11 and one runs DX10. Your Nvidia card will run PhysX but your ATI card will not.Also they have to have the same Memory Clock settings,if they dont they will just run at the slowest one anyway so you will not see any benifit tbh. You can have two different cards,but from the same manufacturer,for example i have 2 4870`s,one is a XFX and one is a powerColor,but both are ATI with the same clock settings.