joaquin85 :
thank you! games like crysis 3 use physx and future games will to so could it be a good idea just to get a 660 ti for better fps on a 2650 x 1600 monitor?
Crysis 3 is not a GPU accelerated PhysX game. Check that link from BigMack, the list is very specific.
http://physxinfo.com/index.php?p=gam&f=gpu
You will only get a boost from a dedicated PhysX card when playing one of the games on that list. The Batman games are PhysX beasts and a good dedicated PhysX card could even help with a Titan on your high resolution. As a rule of thumb, the right dedicated card can boost FPS by roughly 25%
when playing a GPU accelerated PhysX game. Of course, if your Titan is already getting, say, 100 FPS in Borderlands 2, then the dedicated PhysX card would help, but would be overkill.
The key to a good dedicated card is the number of CUDA cores and finding a good balance with your primary graphics card. Selecting a card that is too slow, like the GTS 450 or GTX 280 will slow down your performance. Kepler cards are packed with CUDA cores and make good, efficient PhysX cards, even the cheaper ones. In this case, the GTX 660 Ti will be a good choice; you might even go as low as the GTX 650 Ti or GT 640, but I don't know what your budget is.
So bottom line, yes a PhysX card of a recent generation will help as long as it's not a low-end model, but only on certain GPU accelerated PhysX games. And then, only if you are not already satisfied with the performance of a single GTX Titan running PhysX + graphics on your high resolution monitor.