Added a 2nd Dell 2007FP to my set up and it doesn't work. Display 1 is on the DVI and works fine, display 2 (identical monitor) is on one of two MiniDisplay Ports and it does not work. The display says "Out of range signal. Cannot display this video mode. Go climb a rock." message. 2008 Mac Pro Mavericks ATI Radeon HD 5770 (Mac Edition from Apple). The cable is a brand new MiniDisplay Port-to-DVI cable I got from Monoprice. Thoughts?