What Graphics Setup should i have for this?

Holy crap, man. You have 3x120hz monitors? 😵
That's crazy, you need QUAD SLI setups of 670s or 680s to run games @ 120FPS if you're going to play modern games in surround monitor setup. Checkout this link: http://www.anandtech.com/bench/GPU12/477
Notice how 2x680 in SLI can barely reach 80FPS on BF3 @ Ultra at 5760x1200 resolution. Granted, you can reach more if you lower the settings, but if you want to reach 120FPS on 3 monitors and keep the visuals on Ultra you need massive GPU power.