External monitor not detected

You connected a second monitor or a TV, but the computer does not see it, or the screen says no signal. Check the cable, the screen's input, the display mode and the graphics driver, in that order.

Before you start

Save your work. The screen may flicker or go dark for a few seconds during these steps. Have the monitor's power cable plugged in and the monitor switched on. This takes about 12 minutes in total, and none of the steps delete files.

Try these fixes in order

Fix 1: Check power, cable and input

This takes about 3 minutes.

1. Check that the monitor is plugged in and switched on. A light usually shows when it has power.
2. Push both ends of the video cable in firmly, one at the monitor and one at the computer.
3. Using the buttons on the monitor, open its menu and look for Input or Source. Choose the socket your cable is plugged into, such as HDMI 1 or DisplayPort. A monitor set to the wrong input shows No signal even when everything works.
4. Turn the monitor off and on again, and restart the computer with the monitor connected.

Fix 2: Choose the display mode

This takes about 1 minute. Windows may be set to show only one screen.

On Windows 11 or Windows 10

1. Press the Windows key and P together. A short menu opens on the right.
2. Select Extend. Your desktop should spread across both screens.
3. If it does not, open Settings then System then Display and look under Multiple displays. If a Detect button is shown, select it.

The other choices in the menu are Duplicate, which shows the same picture on both screens, and Second screen only or PC screen only, which switch one screen off.

On a Mac

1. On macOS Ventura and later, open System Settings then Displays. On earlier versions, open System Preferences and choose Displays.
2. Press and hold the Option key. A Detect Displays button appears.
3. Select Detect Displays. A short wait may follow.

Fix 3: Try another cable, another port, and remove adapters

This takes about 5 minutes. A damaged cable is a common cause.

1. Unplug any dock, hub or adapter between the computer and the monitor, and connect the cable straight to the computer if the plugs match.
2. Try a different cable. If the picture appears, the old cable was faulty.
3. If the computer or monitor has more than one video socket, move the cable to another one and select the matching input on the monitor.
4. If you must use an adapter, check that it matches. A USB-C socket only carries video if it supports it, and adapters between connector types sometimes only work in one direction. See USB-C docks, hubs and cables explained and HDMI, DisplayPort, VGA and USB-C explained.
5. Do not use a display splitter to get a second screen. A splitter copies one picture to both screens and cannot extend the desktop.

Fix 4: Reset the graphics driver and restart (Windows)

The graphics driver is the program that sends the picture to the screens. This takes about 3 minutes.

1. Press Windows + Ctrl + Shift + B together. The screen flickers or goes briefly black. This resets the graphics driver.
2. If the monitor is still blank, choose Start, then Power, then Restart.
3. If that fails, choose Shut down, wait until the computer is fully off, and turn it on again.

On a Mac, unplug the display and its power, put the Mac to sleep and wake it, then restart it. Apple also advises installing the latest macOS updates, which include display firmware updates for Apple's own displays. Third-party monitors may have firmware on the maker's website.

Fix 5: Roll back or reinstall the display driver (Windows)

Use this if the monitor stopped working after an update. This takes about 5 minutes.

1. Select the search box on the taskbar, type Device Manager, and open it.
2. Expand Display adapters, right-click your display adapter and select Properties.
3. Open the Driver tab and select Roll Back Driver. If the button is missing or greyed out, go to the next step instead.
4. Right-click the adapter, select Uninstall device, tick Attempt to remove the driver for this device (on Windows 10 it may read Delete the driver software for this device), and select Uninstall.
5. Restart the computer when asked. Windows normally installs a basic driver.
6. In Device Manager, right-click the display adapter again and select Update driver, then Search automatically for updated driver software.

For a driver from the maker of your graphics hardware, use the maker's support site or Windows Update. Never use a driver-updater program. See how to fix driver problems in Device Manager.

If it still does not work

• Connect the monitor to another computer. If it stays blank, the monitor or its cable is probably faulty. If it works, the fault is in the first computer's port, settings or driver.
• Check how many screens your computer's graphics hardware supports. The maker's website lists this. A third screen may not work even when two do.
• If your computer has only one video port, a docking station or a USB-C adapter can add more. Ask the computer's maker which ones suit your model.
• Use the support page on the maker's website for your computer or monitor.

Frequently asked questions