I have a ATI Radeon HD 5770 card in my Mac Pro 5,1 (Mid 2010). It has two Mini Display Port outputs, and a DVI connector. I connected the DVI to my video monitor, and the one of the Mini Display Ports to my Mac. I have another small LCD monitor that I would like hook up through the other Mini Display Port. When I do, my video monitor disappears (DVI). I'm looking for a solution to make this work.