Your LG monitor shows No Signal, followed by Entering power saving mode shortly, when it has power but receives no video. Restoring that video connection is the first job. Start with the input, cable and computer, then use the Windows or Mac fixes that match when the picture disappeared.
Wake the computer and select the right input
This addresses a sleeping computer or the wrong monitor input. Move the mouse or press a keyboard key to wake the connected computer.
Press the monitor’s joystick or control button to open its controls. The button location varies by model. From there, open Input.
Select the connected port, such as HDMI 1 or DisplayPort. Input names vary by model. On the LG 32U889SA Smart Monitor, press Input on the remote instead, then select the connected source.
Check the cable and computer output next
If waking the computer and selecting its input leave the message on screen, check the connection itself. A loose cable, incompatible accessory or incorrect desktop output leaves the monitor without video.
Disconnect the video cable at both ends, then inspect the connectors for damage or debris. Reconnect the cable securely to the monitor and computer. Test the supplied cable or another compatible video cable if the message remains.
On a desktop with a dedicated graphics card, connect the monitor to that card’s video output. LG recommends the motherboard output for PCs without a dedicated card.
For a Windows setup using a dock or dongle, disconnect those accessories, then test a direct computer-to-monitor connection. In a dual-monitor setup where only one screen fails, exchange the monitors’ cables or connection ports to identify which connection fails.
Restore external-display output in Windows
Press Windows+P and choose Extend, Duplicate or Second screen only to match your setup. Use a working laptop screen, secondary display or temporarily restored connection for the settings below.
In Windows 11, open Start > Settings > System > Display > Multiple displays. Select Detect to request another check for the monitor.
Press Windows+Ctrl+Shift+B to reset the graphics driver. If the picture stays off, restart through Start > Power > Restart.
To check for a frozen PC, press Num Lock repeatedly and watch its keyboard indicator; this test is inconclusive on a keyboard without one. If the indicator does not respond, hold the PC’s power button until it shuts down. Turn the PC back on, keeping in mind that a forced shutdown can lose unsaved work.
Get a Mac to recognize the monitor
Check that your USB-C or Thunderbolt cable and adapter support video at the monitor’s resolution and refresh rate. Connector shape alone does not establish compatibility; the connection needs an appropriate standard such as DisplayPort Alt Mode or Thunderbolt.
Replace any incompatible cable or adapter. Disconnect the monitor from the Mac, then disconnect the monitor from power. Reconnect the monitor’s power.
On an Apple silicon Mac laptop, unlock the Mac before reconnecting the accessory. Reconnect the monitor to the Mac. Select Allow if the Mac asks you to approve the connected accessory.
Open Apple menu > System Settings > Displays using a working screen. Hold Option to reveal Detect Displays, then click Detect Displays. Check your exact Mac model’s supported external-display count, resolutions and refresh rates.
Disconnect excess displays to test the LG alone. For closed-lid use, connect the Mac laptop to power. Connect an external keyboard and mouse for use with the lid closed. If detection still fails, sleep and wake the Mac, or restart it.
Undo a resolution or connection-mode change
This addresses signal loss that began after a display-settings change. In Windows 11, open Start > Settings > System > Display on a working display. Select the LG monitor. Under Display resolution, choose the option marked (Recommended).
To test the refresh rate, open Start > Settings > System > Display > Advanced display. Select the LG monitor. Use Choose a refresh rate to select a lower supported rate. Treat this as a test for a mode or bandwidth problem; it does not guarantee a repair.
On a Mac that went blank immediately after a resolution change, wait 15 seconds. Press Esc if the picture does not return. Once you have a usable screen, open System Settings > Displays. Select the monitor.
Choose a supported resolution. Apple recommends safe mode if you cannot restore the previous resolution. On an LG 32UN650 or 32BN67U connected by DisplayPort, open Settings > General > DisplayPort Version.
Select the version supported by the connected device. These models offer 1.4 and 1.2; HDR requires 1.4.
For an LG 32GP850 connected to compatible older equipment without HDMI 2.0, set Settings > General > HDMI Compatibility Mode to On. This excludes 2560 × 1440 at 100, 120 and 144 Hz. Turn HDMI Compatibility Mode back Off if the source does not support it or it causes problems. For other LG models, check the model’s manual for its connection-mode controls and available settings.
Reset the monitor’s power and settings
Disconnect the monitor from power and disconnect all signal cables. Hold the monitor’s power button for 10 seconds. Reconnect the signal cables, then reconnect power. Press the joystick to turn the monitor on.
If the problem continues and the monitor menu works, press the joystick to begin a factory reset. This removes your customized monitor settings. Move right to Settings. For LG general monitors with this menu, select General > Reset to Initial Settings > OK.
For gaming monitors with the alternate menu, select General > Reset > Yes instead. Check your model’s manual if its reset menu differs from these paths.
Adjust timeouts when the picture disappears after inactivity
If waking the computer reliably restores the picture, adjust its idle timeouts. In Windows 11, open Start > Settings > System > Power & battery > Screen, sleep, & hibernate timeouts and increase Turn my screen off after and Make my device sleep after for the applicable power source. These controls change idle behavior; they cannot repair a failed cable or missing startup signal.
On a Mac, open System Settings > Lock Screen and increase the applicable Turn display off… timeout. Display-off and computer-sleep controls serve different purposes.
On the LG 32UN650/32BN67U, disable timer-triggered shutdown through Settings > General > Automatic Standby > Off. Where the model includes Deep Sleep Mode, set Settings > General > Deep Sleep Mode > Off, then test waking the computer again. This tests wake behavior and is not a universal fix for No Signal.
On the LG 32U889SA, disable scheduled sleep through the remote-operated General > System > Time & Timer > Timers > Sleep Timer > Off. This timer is separate from that model’s automatic shutdown after 15 minutes without a signal.
Address persistent computer or monitor software problems
Move to software troubleshooting when input and cable checks have not restored a stable connection. Use a working built-in or secondary screen for computer settings.
On Windows 11, open Settings > Windows Update. Select Check for updates. Install the offered updates. For optional graphics drivers, open Advanced options > Optional updates.
Select the relevant driver and choose Download and install. Restart the computer after installation. If the failure began immediately after a graphics-driver update, open Device Manager > Display adapters.
Right-click the graphics adapter. Select Properties > Driver > Roll Back Driver. This requires an available previous driver.
On a Mac, open Apple menu > System Settings > General > Software Update. Install the offered compatible update. Complete any requested restart.
For monitor firmware, locate your exact model on LG’s software download page. Its listing identifies the software and firmware available for your model and operating system.
For a model supporting firmware updates through OnScreen Control, connect the monitor to an internet-connected computer using a compatible USB data cable in addition to HDMI or DisplayPort. HDMI or DisplayPort alone is insufficient. Open OnScreen Control > Monitor Settings > Monitor Software Update > Run.
For a monitor supporting updates through LG Switch, open LG Switch settings instead. Select Monitor Software Update > Install.
Isolate the fault before requesting service
Use these final checks to separate a computer or connection problem from an unresponsive monitor.
- 1.Try another video output on the computer, then test the LG with a different computer.
- 2.Test the outlet or power strip with another device, then try powering the monitor directly from a wall outlet.
- 3.Reseat the power cord, adapter and monitor plug. If your model has a separate rear DC switch, turn it on before using the main power control.
- 4.Open the monitor’s own menu using its joystick or button, or Settings on an equipped remote. A working menu points toward the computer or video connection.
- 5.If no menu opens after the power checks, seek LG service. On LG’s reset support page, select Chat Now for help or Request a repair when hardware troubleshooting has not resolved the problem.
Frequently Asked Questions
Why are some settings unavailable on my LG monitor?
On the LG 32GP850, OSD Lock restricts access to settings. Open Settings > General > OSD Lock and disable the lock before changing them. Unlocking the menu does not repair the video signal.
Should I turn off SMART ENERGY SAVING to fix No Signal?
LG documents SMART ENERGY SAVING for brightness fluctuations. Turning it off does not restore an absent video signal.
Can my LG monitor switch inputs automatically?
On the LG 32GP850, set Settings > Input > Auto Input Switch > On to enable automatic selection of a newly connected input. Check the model manual for availability on other monitors.
What if my work computer keeps restoring its sleep settings?
Ask IT to review enforced display and sleep timeouts. On managed Windows devices, administrators control these through power-management policies, including Turn off the display (plugged in) and its battery equivalent.