GTX 650 as a PhysX card AND Shadowplay card?

I'm curious about the functionality of Shadowplay in machines where the graphics are primarily handled by an AMD card with PhysX taken care of by a secondary NVidia card (such as the GTX 650 I'm using now).  I'm amazed at the performance of Shadowplay even in it's rather primitive current state, and want to know if I can still use it to record gameplay video in this kind of setup, or if the cost of something like Dxtory will have to be factored into the purchase of an AMD card down the line.

Gonna bump this because I want to do the same thing. I have a 7970 main card and a 650 secondary. 

Well using it for PhysX is kinda pointless because all of about 3 games use it and those that do render it on the CPU but ShadowPlay might be interesting. 

I don't think though it would work though because I believe it reads the frame directly from buffer or something so it can only pull frames if it is also rendering it at well. 

I believe AMD cards have or will have some similar functionality? RadeonPro has video recording I believe.

Yeah you won't be able to use it as a shadowplay card. Shadowplay works by capturing the frames directly from the buffer. If the frames aren't going through the buffer then it won't work. You can do it for PhysX, but as others have said there's minimal benefit to it. All that being said, if you have the parts laying around otherwise unused, why not throw it in for a little bit of fun?