I have a 2009 Mac Pro 4,1 flashed to 5,1 and an Nvidia GTX 680 flashed with the Mac ROM. I recently upgraded my monitor setup to two 30" Apple Cinema HD Displays and one 27" Apple Cinema Display (with mini DisplayPort and USB). The two 30" displays are plugged into the two DVI ports on the 680 and work fine. For the 27" ACD, I ordered a male DisplayPort to female mini DisplayPort adapter (from CableMatters). I could not get the 27" ACD to come on at all for some reason. Previously I used this DisplayPort on the 680 with a DVI adapter to drive another triple monitor display without issue. I was only able to get around this by installing the original Nvidia GT120 and using the mini DisplayPort port on that card, with which the monitor works fine. Is there any way to get this monitor working on the GTX 680? Has anyone run into this before?