What to do if you can't set up dual monitors or they aren't detected

Dual monitor refers to using two screens at the same time on a PC, etc.
You can use it efficiently by opening a work app on one screen and displaying a website for searching on the other screen.
This usage is also called dual display/multi-monitor or multi-display.

If you cannot set up dual monitors or cannot detect them, the following may be the cause:

• Temporary PC malfunction
• Driver malfunction/driver is not up to date
• Not connected properly
• Not configured correctly
• Impact of update
• Monitor failure

This article explains how to solve the problem when you cannot set up dual monitors due to the reasons mentioned above.

What to do if you can't set up dual monitors in Windows 10

If you cannot set up dual monitors or cannot detect them in Windows 10, you may be able to resolve the issue using the following methods.

• Reconnect the monitor after restarting the PC
• Check dual monitor settings
• Run Windows Update
• Reinstall the driver

You may not be able to set up dual monitors due to temporary problems with your PC or incorrect settings.
In this section, we will explain in detail how to solve such problems.

Restart your PC and reconnect your monitor

If you can't set up dual monitors or they aren't detected in Windows 10, restarting your PC and reconnecting the monitors at the same time may resolve the issue.

Temporary problems can be resolved by restarting the PC, and problems such as poor connections can be resolved by reconnecting the monitor.

[How to restart the PC and reconnect the monitor]

1. Shut down your PC.
2. Unplug the monitor and PC power cords.
3. Disconnect the cable connecting the monitor and PC.
4. Reconnect the cable and power cord.
5. Start your PC.

After restarting your PC, check if your monitor is detected.

Check dual monitor settings

If you can't set up dual monitors in Windows 10 or they aren't detected, please check your settings.

If you check the settings, you can see how the display is recognized on the PC side.

[How to check dual monitor settings]

1. Select "Start (Windows mark)".
2. Select "Settings (gear mark)".
3. Select "System".
4. Select Display.
5. Check if the displays labeled "1" and "2" are displayed in "Display".
6. If it is not displayed, select ``Detect''.
7. Select "Expand display screen" or "Duplicate display screen" depending on your purpose.

You may want to select "Extend display screen" if you want to display a separate window on each screen, and "Duplicate display screen" if you want to display the same screen on both screens.

Run Windows Update

If you can't set up or detect dual monitors in Windows 10, running Windows Update may resolve the issue.

[How to run Windows Update]

1. Right-click on "Start (Windows mark)".
2. Select "Settings".
3. Select Update & Security.
4. Select Check for updates.
5. The latest updates, if available, will be executed.

If you think that your dual monitors are no longer detected due to Windows Update, please refer to the following items.
→How to fix Windows 10 monitor not recognized by update

Reinstall the driver

If you can't set up or detect dual monitors in Windows 10, reinstalling the driver may resolve the issue.
There are cases where dual monitors cannot be set up properly because the display driver is outdated, so please try reinstalling the driver by referring to the steps below.

[How to reinstall the driver]

1. Right-click on "Start (Windows mark)".
2. Select "Device Manager".
3. Select "Display Adapter".
4. Right-click the appropriate driver.
5. Select "Uninstall Device".
6. After completion, restart your PC and the driver will be reinstalled.

After restarting your PC, perform steps 1 to 3 again to confirm that the driver has been reinstalled.

Causes and solutions for display not being detected in Windows 10

If the display is not detected on your Windows 10 PC, in addition to the above items, you may be able to resolve the issue by following the steps below.

• Restart your PC
• Discharge your PC
• Check cable connections

There are cases where the display is not detected due to a problem with the PC or cable, so if there is no problem with the settings, please check the condition of the device as well.

Restart your PC

If your display isn't detected in Windows 10, restarting your PC may fix the issue.

The display may not be detected due to a temporary PC malfunction, so if this happens, try resetting the power.

Discharge your PC

If Windows 10 doesn't detect your display, discharging your PC may fix the problem.

When a PC is used for a long time, electricity may accumulate inside it and cause malfunctions.
If this happens, try turning off your PC, removing all cords and batteries, and allowing it to discharge for about 5 minutes.

Check cable connections

If the display is not detected, regardless of whether it is a Windows 10 PC, please check whether the cable is connected correctly.

When connecting an HDMI cable to a PC equipped with a graphics board, connect it to the port on the graphics board, not the port on the motherboard. Be sure to connect to the correct port.

If the problem persists even though the cable connections and settings are correct, try replacing the connected cable with a different one. The problem may be resolved.
In this case, the cause is a deteriorated or damaged cable.

How to fix Windows 10 monitor not recognized by update

If the monitor is not recognized on a Windows 10 PC, an update may be the cause. In such cases, the problem may be resolved by the following methods:

• Completely shut down your PC
• Uninstall the update
• Update your graphics driver

If you know for sure that your monitor was recognized before updating, please refer to this page.

Completely shut down your PC

If your monitor is no longer recognized after a Windows 10 update, a complete shutdown may resolve the issue.

This is because updates may temporarily make the monitor unrecognizable.

A complete shutdown can be performed by holding down the Shift key and selecting Shutdown from the Start menu.

After shutting down, try restarting and see if the problem is resolved.

Uninstall the update

If your monitor is no longer recognized after a Windows 10 update, uninstalling that update may resolve the issue.

If this happens, check the most recently performed update and try uninstalling it.

[How to uninstall updates]

1. Select "Start (Windows mark)".
2. Select "Settings (gear mark)".
3. Select Windows Update.
4. Select "Update history".
5. Select "Uninstall updates".
6. Select the appropriate update.
7. Select "Uninstall".

Update your graphics driver

If your monitor no longer recognizes you after a Windows 10 update, updating your graphics driver may resolve the issue.

If you want to update your graphics driver, try the following methods.

[How to update the graphics driver]

1. Right-click on "Start (Windows mark)".
2. Select "Device Manager".
3. Select "Display Adapter".
4. Right-click the appropriate driver.
5. Select "Update Driver Software".

After updating your graphics driver, check to see if your monitor is detected.

What to do when your display suddenly becomes undetectable

If the display connected to your PC suddenly becomes undetectable, it may be a temporary problem.

Your PC may have gone into sleep mode, so in this case, try waking it up using your mouse or keyboard. If the display suddenly becomes dark and becomes unresponsive, you may be able to recover by pressing or holding down the monitor's power button.

If the issue still persists, please check the following items:
→What to do if you can't set up dual monitors in Windows 10
→Causes and solutions for display not being detected in Windows 10

What to do if your external display isn't recognized

If your external display isn't recognized, updating or reinstalling your device driver or checking your display settings may resolve the issue.

Please check the following items for details.
→What to do if you can't set up dual monitors in Windows 10
→Causes and solutions for display not being detected in Windows 10

What to do if the display is not detected when connected to the VGA terminal

If you connect your PC and display with a VGA cable, but the screen does not appear or is not detected, please check the connection status once.

The VGA cable has screws on both sides, so it will be stable if you tighten these screws as well.

Also, if you have another connection method such as an HDMI cable, you may be able to display the monitor if you try that method.

What to do if the display is not detected on your DELL PC/monitor

If the screen cannot be displayed or is not detected on your DELL PC or monitor, the problem may be resolved by turning off the PC or monitor, reconnecting it, and restarting it.

It seems that the display may not be displayed because the monitor is connected while the power is on.

In this way, if the screen cannot be displayed or is not detected on your DELL PC or monitor, please check the above in addition to the solutions described in the previous items.

How to set up dual monitors on Mac

If you want to use dual monitors with a Mac PC, you will need a compatible cable.
The terminal on the Mac side varies depending on the model. It is good if the monitor supports the same terminals as the Mac, but some only have HDMI terminals. In this case, it is best to connect using a conversion cable.

Typically, your monitor will be detected once you connect it.
If you change the settings or the device is not detected, try opening the menu using the following method and checking.

1. Select the apple mark on your desktop.
2. Select System Preferences.
3. Select Display.
4. You can select settings such as brightness on the "Display" tab, and whether or not to mirror (duplicate the screen) on the "Arrangement" tab.

In this way, you can use dual monitors on a Mac without setting up a monitor by connecting it, but you can make detailed customizations from the settings screen.

Summary of solutions when dual monitors cannot be set up or are not detected

This time, we explained how to resolve cases where dual monitors cannot be set up or are not detected.

Dual monitors can be used by connecting the monitors to a PC and making simple settings, but there are cases where problems with the monitors not being detected may occur due to problems with the PC or monitor.
In addition to malfunctions or malfunctions of the main unit, the cause may also be related to system issues such as drivers or updates, so let's check them one by one.