How to Black Out a Second Monitor from a Stream Deck (Plus a Sleep Timer)

This guide explains the difference between covering one screen and turning screens off, how to set up each key step by step, and what the key's messages mean.

Who this is for

You play on the main monitor and want the second screen dark, for example the second screen of an OLED setup, without unplugging it or digging through its menu.
You want every screen off with one press when you step away.
You leave the PC to finish something and want it to sleep or shut down by itself after 30 minutes or an hour.

Cover one screen, or turn every screen off?

There are two different things you can do to a screen from a key, and Screen Blackout for Windows has a key for each:

Key	What it does	Use it when
Blackout Monitor	Covers one monitor, or every monitor but the main one, with a black window. The other screens keep working.	You want one screen dark while you keep using another, for example while you game.
Screens Off	Turns every monitor off, the same as after the screen timeout in the Windows power settings. Optionally locks the PC first.	You step away from the PC.
Sleep Timer	Counts down on the key. At zero: sleep, hibernate, shut down, turn the screens off or lock.	You want the PC to sleep or shut down later by itself.

The black window of Blackout Monitor covers the picture; the monitor itself stays on. Screens Off uses the same path as the Windows screen timeout, so it acts on every monitor together.

A black window made to stay out of your game's way

The Blackout Monitor window is built to cover a screen without getting in the way of what you are doing on the others:

It is made not to take the keyboard focus, so the game or app you were using should stay in front and keep your keyboard.
It is not in the taskbar or in Alt+Tab, and clicks on the black area do nothing.
When monitors move or change resolution, the black window follows. When the monitor is unplugged, the key shows WAITING and the monitor is covered again when it comes back.
One screen always stays visible, so you never end up with every screen black by accident.

Step by step: black out a monitor

Install Screen Blackout for Windows from the Elgato Marketplace. It runs on Windows 10 or later with the Stream Deck app 6.9 or later and Windows PowerShell 5.1, which is part of Windows.
In the Stream Deck app, find Screen Blackout for Windows in the action list and drag Blackout Monitor onto a key.
Under Monitor, choose a monitor (listed by number, name, size and position) or Every screen except the main one. Press Refresh the list after you connect a monitor.
Press the key: a black window covers that monitor and the key shows BLACK. Press again to uncover it.
Optional: tick Uncover while the mouse is on it. Moving the mouse onto the black monitor shows it, and it turns black again when the mouse leaves.

Other ways to uncover:

Hold any Blackout Monitor key for about a second to uncover every black screen.
Double-click the black area. This works even without the Stream Deck.
The black window also goes away when its key is no longer shown (you switch to another page or profile, remove the key or unplug the Stream Deck), and when you close the Stream Deck app.

Step by step: turn every screen off

Drag Screens Off onto a key. Optional: tick Lock the PC first.
Press the key. Windows turns every monitor off. Move the mouse or press a key to turn them on again; some monitors take a few seconds.

Step by step: set a sleep timer

Drag Sleep Timer onto a key and choose what happens At zero: sleep, hibernate, shut down, turn the screens off or lock the PC.
Choose how a press works. Each press can add time (5 minutes to 1 hour per press, up to a limit of 1 to 12 hours), or start a fixed time (15 minutes to 4 hours; a press while it runs starts it again).
Press the key. It counts down: 14:59 (minutes:seconds) under an hour, 1:05 (hours:minutes) from an hour. It blinks in the last minute.
Hold the key for about a second to cancel. Nothing happens at zero then.

The timer is built so it never surprises you later. It runs only while its key is shown: switching to another page or profile, removing the key or unplugging the Stream Deck cancels it, so no hidden timer can turn the PC off. If the PC sleeps for another reason or the clock changes while it runs, the timer is cancelled and the key says why (the PC slept or the clock changed) instead of acting right after the PC wakes up. A running timer is not saved, so a restart of the PC, the Stream Deck app or the plugin cancels it.

What the key's messages mean

The key shows	What to do
`LAST SCREEN`	Covering that monitor would make every screen black, so the plugin leaves it visible. To turn every screen off, use Screens Off.
`NO 2ND SCREEN`	"Every screen except the main one" was chosen, but only the main monitor is connected.
`WAITING`	The chosen monitor is not connected. It is covered again when it is back.
`STOPPED`	The helper (Windows PowerShell) that shows the black windows ended, so they are gone. Press the key to try again.
`ERROR`	The helper could not start or answer. The "Now" line in the key's settings says why. Some company PCs block Windows PowerShell or its Add-Type command; the plugin cannot work there.
`NO SLEEP`	This PC has no classic sleep (S3); many newer laptops use Modern Standby instead, which a program cannot start. Choose hibernate, turn the screens off or lock.
`NO HIBERNATE`	Hibernation is turned off on this PC. An administrator can turn it on with `powercfg /hibernate on`.

Two more things to know. On a covered monitor, a game in exclusive full screen on that same monitor, the mouse pointer, notifications and some windows that also stay on top can still show. And at zero, an app with unsaved work can stop a shutdown, just as with Start > Shut down, so save your work before you leave.

Frequently asked questions

How do I black out my second monitor with a Stream Deck?

Install Screen Blackout for Windows, drag Blackout Monitor onto a key, choose that monitor (or Every screen except the main one) in the key's settings, and press the key. Press again, hold the key, or double-click the black area to uncover it.

Will the black window take focus away from my game?

It is made not to take the keyboard focus, so the game or app you were using should stay in front and keep your keyboard. It is not in the taskbar or in Alt+Tab, and clicks on the black area do nothing.

Can I turn every screen off with one key?

Yes. Screens Off turns every monitor off, the same as after the screen timeout in the power settings, optionally after locking the PC. Move the mouse or press a key to turn them on again.

How does the sleep timer work?

Each press adds time, or starts a fixed time. The key counts down and blinks in the last minute, and at zero the PC sleeps, hibernates, shuts down, turns the screens off or locks, as you chose. Hold the key to cancel.

Does blacking out a monitor turn it off?

The black window covers the picture; the monitor itself stays on. Whether that helps an OLED monitor depends on the monitor, so check its manual. To turn every screen off, use the Screens Off key.