i think the 580 can only support 2 displays, to have 3 or 4 you need 2 cards, different size screens are easly set up in non sli mode, so dont expect to play games across all different size screens, but it should work great for desktop
1. WTF............580s ?
2. Yea, u need Dual GPU for Tri-screen for Nvidia cards
3. Get the same monitors, save urself from the trouble
4. How much is your income? seeing you're willing to spend 500 bucks on another card