I cant put an extract card in my machine
You could always try to crack the code on the lock for the drivers and force PhysX out of the AMD Steam Processors. It might work but that'll require some programming knowledge.
i was under the impression that adv. physx had somethiing to do with a dedicated chip on the card, one of the reasons not all cards supported it
besides i don't understand why people care about it so much to do spend cash on a second card and spend time to try to force it on an amd card, i've seen physx, i'm not impressed, i've seen games running with and without physx, they looked almost identical
Its not because of a chip, heck it can be done on the cpu though that usually needs it being done at lowest settings because ether cheap/lazy devs that wont multi-thread properly, nvidia paying them off or direct x 9(because according to the article dx9 limits to 2 cores, not sure I believe that).
Below shows metro 2033 dev's I think it was got multi-threaded physx working in dx11 mode for the game and it was comperable to nvidia's gpu based physx. If it can be properly done on a cpu it can probably be done right on an amd gpu too. Admittedly I'd rather see tressfx become the dominant gpu based physics system because it already runs on all gpus and the next gen consoles have amd so hopefully.
http://www.tomshardware.com/reviews/nvidia-physx-hack-amd-radeon,2764-5.html