Hybrid Phys-X GPUs

So, I have a 7970 and am wanting to play Phys-X games such as Borderlands 2 w/ Phys-X actually on at more than 15fps. I know Phys-X is hated by some but it's something I want for my own personal reasons. Simply put, many of the games I love playing support Phys-X. 

I know you can run an AMD card w/ a Nvidia card dedicated to Phys-X but I was wondering what the best card would be for such usage and also what would be potential benchmarks for such a system. If you aren't aware of hybrid GPU's, as I wasn't before buying my 7970, here's a forum about it (sorry if this breaks some rules, first time forumer) http://www.overclock.net/t/1307142/borderlands-2-with-hybrid-physx

Thanks in advance

a 550Ti is enough to handle PhysX in all modern games out right now. You can pick one up for about $100.

http://www.youtube.com/watch?v=cbww3dhzK0M

I was looking at the 650 also. Not seen much about it as a Phys-X card but it benches higher than the 550ti or similar in most circumstances. Reckon that will do the job?

correct me if i'm wrong but you can't run a dedicated Phys-X Nvidia card with a AMD card, (at least not without hacking the drivers) as far as I know you need 2 Nvidia cards to do this

The thread in that forum talks about how to do it. Indeed it is modified drivers. Nothing too complicated though, just enough so the Nvidia card doesn't find the AMD card and shit the bed.