hello i have an sapphire radeon hd 7850 2gb gddr5 and i am running it at 2 montiors. my question is if i buy a graphic card what is best? and what do i have to look for in a graphic card to max the fps? should i buy a navida card and run 1 on that and the other on my radeon or should i buy another radeon. and what kind of graphic card can i buy to fit with my radeon
Obviously, the best card you could buy would either be a 7950 or 7970 (GHz Ed.). However, AMD's crossfire makes things interesting since it doesn't have to pair with identical models like SLI, but rather, just a card of the same family. That means you can get a 7870 and run it in CrossFire with the 7850. With games that support it, it should give better performance than a single 7970, but your mileage will vary, which is why a single card is usually recommended.
Having more memory would be great, but it won't increase FPS, but rather prevent frame-dips in particular memory intensive games, especially at resolutions you get from multiple monitors. I think 2GB would be fine for 2 monitors, but if you step up to 3, you may want to consider a powerful single card with at least 3GB of memory. Again, 7900 series come to mind, especially since those cards excel at higher resolutions compared to the competition.