If a monitor detects no dvi-d cable, preparing to enter power save mode in 5 minutes
This may happen sometimes: A monitor suddenly fails to detect the DVI-D connection, although working without problems for days or weeks! Then it announces that power save mode is going to be activated in 5 minutes! There is no documented reason why this happens, if it is a problem of the graphics driver or of the monitor itself, etc, but you have some ways to fight it.
An easy way would be to use the power button of the monitor to turn it off, and then back on again, perhaps after a few seconds. A second way would be to restart Windows, which means interrupting works and tasks currently running. The first way is convenient, but it may not work, while the second is always effective — until of course the time comes for your monitor to become again ‘blind’ to the DVI-D connection.
A third way, which I recommend, is to just let the 5 minutes pass. Your monitor will enter power save mode, and the next time you give a power save command, it will obey without DVI-D connection problems. Of course, the time will come for the problem to reappear. You can receive it as a free 5 minutes time to make a coffee or whatever!
Check also how to put your monitor to power save mode easily, with Sleeper.