How to get completely blank screen when display is shut off.

Windows 10 - 1909 Using Control Panel > All CP Items > Power Option > Edit Power plan settings. I can set the timeout for the screen - it's an external monitor connected to a notebook computer. For experimenting, I set the value to 1 minute under "When plugged in", and the screen goes blank as expected.

However, the monitor backlight is still activated so the screen is dark gray instead of pure black. It's noticeably different than the notebook screen which is completely black. When I move the mouse to reactivate, the external monitor backlight goes out for a few seconds, and screen goes completely black before it "comes alive" with the actual program content. I've tried every combination of power options and screensavers I can find to try to make it go completely black. I **think** it used to go completely black until perhaps six months ago, but I can't be certain. Recently purchased a new external monitor, and it behaves the same as previous monitor. I've begun turning off the monitor so it doesn't light up the room in the middle of the night, which is a minor annoyance.

How can I make the screen go completely blank when the computer is not being used, other than using the monitor power switch?

Does your monitor briefly show a "no signal" (or similar) display when the PC timeout expires? If it does and still the backlight stays on ... then you're stuck. That's the way the monitor works. (Most seem to work that way.)

margrave55 said:

Does your monitor briefly show a "no signal" (or similar) display when the PC timeout expires? If it does and still the backlight stays on ... then you're stuck. That's the way the monitor works. (Most seem to work that way.)

It does not flash the "no signal" message, and the overall response is not what I wanted to hear, but I guess that's just the way it is. I must have mis-remembered previous condition. Thanks for the reply.

Hello @jacksonmacd and welcome to TF,

I have a solution as the same issue bugs me too .

You have to download a third party app:
https://www.nirsoft.net/utils/nircmd.html
Then open a command prompt from the folder where you unzipped the zip containing nircmd.exe and issue the command just to see if works:
[command]nircmd.exe monitor off[/command]

Now if that works well enough for you, then

Create a new Task using Windows Task Scheduler:
(use option 1: Windows 10: Create Scheduled Task)
Triggers: on the event "On workstation lock" and
Actions: Program/script: "full-path\nircmd.exe" , Add arguments:"monitor off"
Conditions: Uncheck the boxes related to power.
Settings: Uncheck all but the first checkbox.

Save the new Task and test it by running it manually to confirm the monitor turns off.
If the task works, lock your PC with Win+L and you should have your black screen with no back light - at least it works that way for my laptop and desktops with external monitors.

You can also just create a shortcut you can click to immediately turn the monitor off anytime.

jacksonmacd said:

How can I make the screen go completely blank when the computer is not being used, other than using the monitor power switch?

I use a blank screen saver.

OldNavyGuy said:

I use a blank screen saver.

This works well if you can wait for the configured wait time. The method I posted will blank the screen immediately upon Win+L.

badrobot said:

I think that issue is not controlled by Windows anymore. You monitor is still powered on. You have to check if your monitor has a configurable sleep timer or power off timer so it will shut off together with your windows after a specified time.

I can make my monitors turn pitch black by the method I posted or blank screen saver without turning them off. Unclear what you mean?

Jacee said:

Can you keep that setting for a specified time, such as 6 or 8 hrs?

I haven't tested that duration as I have my PCs configured to sleep way before 6-8 hours, but I don't see why it would not work for that duration unless something else on the PC wakes the PC.

What I have tested in Win+L will make my screen turn black within a few seconds vs showing the lock screen for x minutes.