You CAN connect 3 monitors without losing much FPS. This topic has been discussed already.

Just set all 3 monitors to function as one in a horizontal span and you will maintain 35+ FPS (which is more than necessary) even in Shattrath or 25 man raid setup - even at max settings. Make sure to set the resolution to fit each monitor.

You can connect 2 of your monitors into your GTX and connect the 3rd into your motherboard directly (if the mobo has a video port). Otherwise, you might want to split one of your ports in the GTX (though I haven't tried this - I might tonight) to connect 3 monitors into one card.