I recently revived my early 2008 Mac Pro 3,1 along with my 30′ Cinema Display and my 22′ Cinema display. I tried plugging in the two monitors into their respective female DVI ports on the Mac pro, but only one monitor is recognized. I switched the plugs around, and whichever monitor is plugged into the rightmost port works, while the other remains black and unrecognized. Why is this? Is there an adapter I need in order for both to work? Thanks!