How to deal with the disappearance of the monitor from the system when the power is turned off?

Question

Monitors

Hello.
Monitor DELL U2417H, Video card Gigabyte GTX 1080 G1 Gaming, Windows 7 x64.
The monitor is connected via the included DisplayPort to DisplayPort Mini cable.
When the power is turned off on the monitor, the monitor itself disappears in Windows (with the corresponding sound signaling that the device is turned off), which causes the location of the windows to fly off - the second monitor (Asus, connected via HDMI) becomes the main one - all windows and, in general, the entire desktop are thrown at him.
Google suggested that in some cases, connecting through a different connector (DVI, for example) can help. But the video card has only three DisplayPort connectors and one HDMI, to which a second monitor is connected (the second monitor has only HDMI, DVI and D-Sub inputs).
The question is, how can you defeat such a disappearance of the monitor from the system?
upd: By the way, I checked with the HDMI cable - the monitor does not disappear when turned off (disappears only when the cable is pulled out).
It is possible that with a DP -> HDMI adapter the problem will be solved.
upd2: I took the DP -> HDMI cable and the problem disappeared. When the monitor is turned off, the system still makes the sound of the device being turned off, but the screen settings, windows, etc., do not go astray. At the same time, if you turn off the computer, the monitor does not turn off the screen immediately, but writes something like “cable not connected” on a gray screen and there is a five-minute countdown before going into standby mode (when connected via DP, it went into standby mode immediately; and , if I remember correctly, the waiting time can be changed in the settings).

Answer 1

Monitor off = not present. Why would any windows stay there?