Have just purchased and installed a FirePro W4100 to run 4 monitors (replacing 2 Quadro 600 cards). Software recognises 4 monitors are connected, but only allows extension to 3. When extending to the 4th, the 2nd display is disabled. Does anyone know of a fix to get the 4th display working, or do I need to go back to the Quadro cards? All displays are connected using mini DP to DVI cables.