A second monitor that keeps going to sleep is usually losing its video signal because of power saving, a loose cable, or a dock or USB-C connection dropping out. The monitor sees no active signal and powers itself down. Check and reseat the cable, disable the monitor's deep-sleep or eco mode, set its input to fixed rather than auto, and adjust your power settings.
Why this happens
- The monitor's own auto power-off, eco, or deep-sleep feature turns it off when it thinks the input is idle.
- A loose, damaged, or low-quality cable or adapter is intermittently dropping the signal.
- A docking station or USB-C hub is losing power or connection, cutting the video to that monitor.
- The monitor's input is set to auto-detect and keeps switching away from the correct source.
- Windows power management is suspending the port or the display after idle time.
- An outdated graphics driver or dock firmware handles the second display poorly.
Is this normal?
A monitor sleeping when the computer is truly idle is normal. A monitor that sleeps while you are actively using the main screen, or that will not wake without unplugging, is not normal and needs attention.
Does it cause any problems?
It is disruptive rather than damaging. Every time the second monitor drops, windows can rearrange onto the remaining screen, and you lose your layout. Fixing the cause keeps your workspace stable.
How to fix or check it
- Reseat the cable at both ends, and try a different cable and a different port. A weak connection is the most common cause.
- Open the monitor's on-screen menu and disable any deep-sleep, eco, or auto power-off option.
- Set the monitor's input source to the exact port you are using instead of "auto", so it stops searching for a signal.
- Windows: In Settings, System, Power, set the display to turn off after a longer time or never while plugged in.
- In Device Manager, open the display adapter and USB controllers, and turn off "Allow the computer to turn off this device to save power" under Power Management where available.
- Update your graphics driver, and if you use a dock, update its firmware or connect the monitor directly to test.
- Mac: Check System Settings, Displays and the Battery or Energy settings, and test without the dock to see if the dock is the cause.
Frequently asked questions
Why does only my second monitor sleep and not the first?
The second monitor often uses a different cable, port, or dock, any of which can drop the signal. That connection is the first thing to check.
My windows move when the second monitor sleeps. How do I stop it?
Stop the monitor from losing signal by disabling its deep-sleep mode and securing the cable, so the computer keeps seeing it as connected.
Could my dock be the problem?
Yes. Docks and USB-C hubs are a frequent cause of a dropping second display. Connect the monitor straight to the computer to confirm.