Not sure if im on the right track here. But i thought if you added more video cards you have to make sure first your computers power supply can handle the added power. If not you will not only have to buy another video card but a bigger internal power supply.

This is the only reason why mine has a huge power supply so i can add another video card. Plus im going with a different video card then i have one that can handle three monitors like a 2gb one. My 1gb one is fine for two screens, but with more screens i want a bigger one.

From what a computer tech told me is that it doesnt matter if they are different as long as there is room and you dont over heat system.