Your Samsung monitor shows “Check Signal Cable” instead of a picture. Some models use the longer message, “Check the cable connection and the settings of the source device.” Start with the connected device, input, and cable, then use the Windows, Mac, or monitor settings below to narrow down the fault.
Wake the connected device first
This fixes a missing picture caused by a computer or console that is off or asleep. Turn on the connected computer, laptop, or console. Wake the device if it is sleeping. Restart the source device if the message remains.
Restart the monitor. Check whether the picture has returned.
Make sure the monitor is watching the right input
The selected input must match the port your cable uses. A cable plugged into HDMI will not supply a picture while the monitor is watching DisplayPort. Press the monitor’s Source button. On models with a JOG control, open the input selector with that control instead.
Select the input matching the connected port. On a Samsung Smart Monitor, open Home > Source with the remote. For the newer interface, use Home > Menu > Connected Devices.
Select the connected computer. If the correct input still gives you no picture, reconnect and test the video cable next.
Reconnect the cable and isolate the faulty connection
These checks separate a loose connection from a faulty cable or source device.
- 1.Power off the computer and monitor.
- 2.Disconnect the video cable at both ends, then reconnect it firmly. For a single-picture setup, remove any second video connection between the same computer and monitor. Keep separate USB peripheral connections connected.
- 3.Turn both devices on, then use Source or the JOG input selector to select the connected input.
- 4.Try another compatible video cable between the same devices.
- 5.Test the original cable with another device.
- 6.Connect the monitor to another computer or video source using a known-good cable.
Check the USB-C port and bypass the dock
A USB-C port or cable without video support leaves the monitor without a picture. Connect the monitor directly to the computer, bypassing any dock or adapter. Test another video-output port on the computer if it has one.
For a Samsung Smart Monitor M80B, connect the computer to the left USB-C port when viewing the monitor from behind. The other USB-C port is for peripherals. This placement applies to the M80B, not every Samsung monitor.
Use the M80B’s specified USB-C 3.1 Gen2 10G cable supporting video. For an M80B connection targeting 3840×2160 at 60 Hz, stop active USB transfers before changing the USB-C preference.
Open Home > Menu > Settings > All Settings > Connect > External Device Manager > USB-C Preference setting. Select High Resolution.
For a Mac, check the cable or adapter specifications for support for your display mode through DisplayPort Alt Mode or compatible Thunderbolt. Check the Mac’s specifications for its supported display count, resolution, and refresh rate.
Get Windows to send a picture
A connected cable is only part of the setup. Windows also needs external-screen output enabled. Use your laptop screen or another working display for these Windows 11 settings.
Press Windows+P. Select Extend. Duplicate and Second screen only also enable external output; PC screen only does not.
Select Detect under Start > Settings > System > Display > Multiple displays. For a setup that suddenly stopped working, press Windows+Ctrl+Shift+B to reset the graphics driver without uninstalling it.
If the shortcut does not help, select Start > Power > Restart. If the problem began after a display-setting change, open Start > Settings > System > Display.
Select the Samsung display. Set Display resolution to a supported option, normally the one marked (Recommended).
Open Advanced display to adjust the refresh rate. Select the Samsung monitor. Use Choose a refresh rate to select a rate supported by the monitor’s input, cable, and resolution.
If an unsupported setting prevents access to the display, hold Shift while selecting Power > Restart to enter recovery. Have your BitLocker recovery key ready if the PC is encrypted. Select Troubleshoot > Advanced options > Startup Settings > Restart. Press 3 for Enable low-resolution video to regain access to the display settings.
If the picture still does not return, select Start > Settings > Windows Update > Check for updates. Install applicable updates. Restart when requested.
If the failure began immediately after a graphics-driver update, open Device Manager > Display adapters instead. Rollback requires a previous driver to be available. Right-click the GPU. Select Properties > Driver > Roll Back Driver.
If these Windows fixes fail, use the monitor’s diagnostics below to check its own picture, then follow the service decision based on your cable and source tests.
Restore the connection on a Mac
These checks address display detection, blocked accessories, and closed-lid operation. Open Apple menu > System Settings > Displays. Hold Option while clicking Detect Displays.
On an Apple-silicon Mac laptop with a blocked display or adapter, unlock the Mac. Reconnect the accessory. Select Allow when asked to approve the connection.
For closed-lid use, connect the Mac laptop to power. Connect an external keyboard. Connect an external mouse. Approve the display and accessories before closing the lid.
If the picture disappeared immediately after a resolution change in macOS Tahoe 26, wait 15 seconds for it to return automatically. Press Esc to restore the previous resolution if the picture has not returned.
Match an Odyssey monitor’s connection settings
On supported Odyssey models exposing DisplayPort Ver., including the G81SF, open Menu > System > DisplayPort Ver.. An incorrect setting causes a blank screen on affected setups. Select a version supported by the connected graphics hardware.
For a blank HDMI picture on an Odyssey model with Input Port Ver., open Menu > System > Input Port Ver.. Select 1.4 to test HDMI compatibility. This limits supported resolutions and refresh rates; higher-bandwidth modes require 2.0↑.
On supported Odyssey monitors showing the newer cable/source-settings message, open Menu > System > PC/AV Mode. Select the connected HDMI1, HDMI2, or DisplayPort input. Choose PC for a computer or AV for the corresponding audiovisual source.
If intermittent blanking follows variable-refresh operation, open Menu > Game on a compatible model. Set FreeSync Premium or FreeSync Premium Pro to Off. For the corresponding NVIDIA configuration, set Adaptive-Sync to Off instead. Retest using a fixed resolution and refresh rate supported by the connection.
Match these controls to your exact model; there is no universal DisplayPort version or refresh rate that fixes every Samsung monitor.
Use the monitor’s diagnostics to narrow it down
On supported monitors, the internal diagnostic is at Menu > Support > Self Diagnosis, or under System on models with that layout. Picture Test, where offered, assesses the monitor’s picture.
Smart Monitors use Settings > All Settings > Support > Device Care > Self Diagnosis. On supported models from 2022 onward, HDMI Troubleshooting tests the HDMI port selected within that diagnostic.
The cable-disconnected self-test is another option on supported Samsung models. Its sequence starts with the computer and monitor off, followed by disconnecting the signal cable from the computer and turning only the monitor back on.
A moving Check Signal Cable box is the expected self-test display. It confirms basic display operation, but it does not establish that every input circuit is healthy.
Reset the monitor or arrange a repair
A reset restores the monitor’s settings to factory defaults. On Odyssey G60SD, G61SD, G81SF, and G90XF models, select Menu > Support > Reset All. On other Samsung families that place the control under System, use that location.
Reselect the connected input after the reset. For a Smart Monitor with the software-update interface, connect it to the network. Select Settings > All Settings > Support > Software Update > Update Now.
Allow installation and restart to finish. For other models, look up the exact model code in Samsung’s Manuals & Software downloads.
Follow that model’s firmware installation instructions. Both the firmware and update procedure must match the monitor.
If these steps fail, request service through Samsung’s Support Center when the internal diagnostic fails or the monitor still fails with another source and a known-good cable. If another source works, seek help for the original computer or its graphics hardware.
Frequently Asked Questions
Can my Samsung monitor switch inputs automatically?
Supported Odyssey models, including G60SD, G61SD, and G81SF, offer this feature. Open Menu > System > Auto Source Switch+. Enable it to let the monitor select a newly connected source automatically. Availability depends on the model and region.
My M80B does not recognize my computer as a PC. How do I change that?
Open Home > Menu > Connected Devices. Highlight the computer. Press the down directional button. Select Edit > Edit Device Type > PC. This corrects the device classification; it does not repair a faulty cable.
Can I use wireless screen sharing while troubleshooting the cable?
On compatible Smart Monitors, open Home > Source > Connection Guide > PC > Screen Sharing (Wireless). Follow the connection prompts. The monitor and source device must meet the network requirements. Wireless sharing bypasses the cable connection.
What if my work Mac blocks the monitor or adapter?
On a supervised Apple-silicon Mac laptop, the administrator controls accessory-connection permissions. Ask your administrator to review the managed accessory setting if approval is restricted. Apple provides these controls through Apple Configurator.