Guide
Why is my external monitor not detected?
Troubleshoot an external monitor by checking power, input selection, cable path, port capabilities, display settings, adapters, and graphics support.
At a glance
- First checks
- Power, correct input, and cable seating
- USB-C caveat
- A USB-C port may or may not support display output
Overview
A monitor can fail to appear because of a simple input-selection problem, a bad cable, an adapter limitation, a port that does not carry video, a graphics-driver issue, or unsupported resolution and refresh combinations. USB-C ports are especially easy to misread because identical-looking connectors can support different video capabilities.
Prove the signal path
Verify the monitor works on the selected input, reseat or swap the cable, and test another known-good display or source when available. Check the laptop or desktop documentation to confirm the specific port supports video output.
Then check software
Use the operating system's display-detection controls, restart the graphics stack by rebooting, and confirm the requested resolution and refresh rate are supported by the monitor, adapter, cable, and source port together.
Sources and review
MOOR's explanatory text is supported by the following source links.
- Troubleshoot external monitor connections — Microsoft Support
- USB Type-C Cable and Connector Specification — USB Implementers Forum