I use an Acer XB270H as my primary monitor and just a cheap Dell secondary monitor along with a 780 acx sc. Just recently I lost signal to my Acer through the display port while the Dell is plugged into the 1st DVI port. The Dell gets the "extended desktop" display. But when the Acer is plugged into the display port and the Dell is plugged into the 2nd DVI port, both monitors work properly... Can anyone tell me why this is happening and how to fix it?