I have two Radeon 6450 graphics cards in my computer, with three screens. Only the screens plugged into the first graphics card are recognized and configurable in the displays setting panel. How can I use the displays plugged into my second graphics card? Both cards are present in lspci: 01:00.0 VGA compatible controller: ATI Technologies Inc NI Caicos [AMD RADEON HD 6450] 01:00.1 Audio device: ATI Technologies Inc NI Caicos HDMI Audio [AMD RADEON HD 6450] 02:00.0 VGA compatible controller: ATI Technologies Inc NI Caicos [AMD RADEON HD 6450] 02:00.1 Audio device: ATI Technologies Inc NI Caicos HDMI Audio [AMD RADEON HD 6450] I'm using the open source driver instead of the proprietary driver because the proprietary driver won't output 1440x2560.