I have a Nvidia Geforce gtx 660, and the other day the feed from the DVI-D port just disappeared out of nowhere! I have tried hooking up a different monitor, and using a different cable, but no luck. My computer thinks that it's working fine, it registers the monitor, and when I'm using dual screens, I can even move the cursor or drag windows into the dead zone.
I have tried both updating and rolling back my graphics card drivers, as well as doing the Windows Refresh (I have Windows 8.1), and it hasn't worked.
This is incredibly frustrating because I really like having dual monitors to do my designing.