External Display Not Working? Try These 15 Fixes for macOS

External Monitor Not Working Featured

Using an external display with your Mac should be as easy as connecting the cable, but what if nothing shows up when you plug it in? In this tutorial, we share all the fixes, tricks and techniques you can try to fix the external display not working issue in macOS. These tips apply to both Intel-based and the more recent M1-based Mac computers.

Before We Begin: Are You Sure Everything’s Connected Correctly?

Let’s get the obvious out of the way first and make sure your external monitor and Mac are set up correctly. Follow the instructions here to make sure your external monitor is connected properly.

If you’ve followed the above instructions and your external display still isn’t working correctly, then you can try the following fixes:

1. Disconnect and Reconnect

Let’s start with the simplest fix: turn it off and then back on again! There are a few different techniques you can try:

  1. Disconnect your adapter for 10 seconds.
  2. Reconnect the adapter.

If this doesn’t yield results, then:

  1. Disconnect your adapter.
  2. Power down your Mac.
  3. Reattach your adapter.
  4. Power up your Mac.

Some users have also reported positive results by switching their monitor on and off while also removing and reattaching the cable:

  1. Unplug the cable.
  2. Switch off your monitor.
  3. Reattach the cable.
  4. Switch on your external monitor.

Finally, if you’re using a MacBook, MacBook Air or MacBook Pro, you can try disconnecting while also closing your Mac:

  1. Connect your Mac to the external monitor.
  2. Select the “Apple” logo in your Mac’s menu bar.
  3. Click “Restart,” then immediately close your Mac’s lid.

2. Check Your Cables

Just because a cable looks connected doesn’t mean that it is connected securely. Even a slightly loose connection can prevent your Mac from recognizing the attached display. If you’re experiencing issues with an external display, then it’s always worth detaching your cable and adapter, then re-attaching them firmly.

3. Don’t Rely on Battery Power

If you’re running your MacBook from its internal battery, it may not have enough power to push pixels to an external monitor. Try attaching your MacBook to a power outlet to see whether this gives your laptop the juice it needs to power an external monitor.

4. Check Whether Your Operating System Is Up to Date

If your operating system is out of date, then you may be encountering an issue that’s already been addressed in a recent update. You should check that you’re running the most recent version of macOS.

External Monitor Not Working System Update

5. Let Your Mac Take a Power Nap

Similar to the “turn it off and back on again” method, you may be able to kickstart the connection by letting your Mac take a quick power nap:

  1. Select the “Apple” icon in your Mac’s menu bar.
  2. Select “Sleep.”
External Monitor Not Working Sleep
  1. Wait a few minutes.
  2. Wake your Mac by interacting with its trackpad or mouse, or by pressing any key on the keyboard.

6. Remove Any Chained Adapters

You can’t force a Mac to play nicely with an incompatible external display by chaining multiple adapters together!

If you have a chain of adapters, such as a Mini DisplayPort to DVI adapter chained to a DVI to HDMI adapter, you’ll need to replace this setup with a single, compatible adapter.

7. Check the Brightness, Contrast, and Resolution

Your Mac’s brightness, contrast and resolution settings can prevent your display from appearing on an external monitor.

To check that these display settings aren’t interfering with your external monitor:

  1. Select the “Apple” logo in your Mac’s menu bar.
  2. Navigate to “System Preferences -> Displays.”

You can now look for any unusual or extreme settings or experiment by dragging the various sliders inside the “Displays” Settings menu.

External Monitor Not Working Displays

You can also check that the brightness isn’t cranked down on your external display using the Ctrl + F2 keyboard shortcut.

8. Check Compatibility of External Monitor

There are quite literally hundreds of monitors available in the computer marketplace, but not all of them are going to be compatible with your Mac. That’s true even if you use what should be compatible cables. One important note is that Thunderbolt 3 and USB-C ports look similar, but are not the same. Go to “Apple -> About This Mac -> System Report” and verify which ports your computer has, then find a monitor that has compatible ports.

External Monitor Not Working System Report

9. Test with an Alternative Monitor

If your monitor is buggy, temperamental, or outright broken, then no amount of adjusting your Mac’s settings is going to fix the problem! If you have access to a second external display, try attaching it to your Mac to see if it works. If yes, then this strongly indicates that the problem lies with your external monitor.

10. Check Your Graphics Card and Drivers

If you’re using a third-party graphics card, check that the card is seated fully in the Peripheral Component Interconnect (PCI) slot and that you have the very latest version of all the necessary drivers. New versions of macOS sometimes include driver updates, so you should also check that you’re running the latest version of macOS.

11. Use macOS’s Hidden Detect Displays Feature

If macOS doesn’t recognize your external display automatically, you can try to force the connection using macOS’s Detect Displays feature:

  1. Select the “Apple” logo in your Mac’s menu bar.
  2. Navigate to “System Preferences -> Displays.”
  3. Press and hold the Option key, and a “Detect Displays” button should appear.
  4. Select “Detect Displays” to see whether macOS recognizes the attached display.

12. Resetting NVRAM: Wipe Your Non-Volatile RAM

Non-volatile random-access memory (NVRAM) is a small amount of memory where macOS stores all the settings it needs to access quickly, including some settings related to the display.

If these settings become corrupted, then it can cause a range of technical issues, so resetting your NVRAM may resolve the issues you’re experiencing with your external monitor.

Before we begin, be aware that resetting NVRAM will also reset your system settings and preferences, so you may need to spend some time reapplying these settings following an NVRAM reset.

To reset NVRAM on Intel-based Macs:

1. Shut down your Mac as normal.

2. Power up your Mac and immediately press the Option + Command + P + R keys.

3. Hold these keys until macOS restarts, then release them.

M1 Macs don’t have a keyboard shortcut to reset NVRAM. The system automatically checks whether a reset is required during startup. If you want to enforce this check, shut down your Mac and restart it after a few seconds.

You’ve now successfully reset your Mac’s NVRAM and can check whether macOS is playing nicely with your external display.

13. Try Resetting macOS’s SMC

The System Management Controller (SMC) is a chip that controls many of your Mac’s physical components, so resetting SMC can resolve certain display-related issues. (You can skip this step if you have an M1 Mac, as Apple Silicon Macs don’t come with an SMC.)

To reset SMC:

  1. Make sure your Mac is completely switched off.
  2. Connect the power adapter.
  3. Press and hold the Control + Shift + Option keys and the “Power” buttons for 10 seconds, then release all four keys at once. If your MacBook has the T2 chip, you’ll need to use the Shift key on the right side of your keyboard in addition to the other keys.
  4. Restart your Mac as normal.

14. Using 4K? Make Sure Your Mac Is Compatible!

If you’re using a 4K external display, then there’s no guarantee that your graphics card will be powerful enough to push all of those pixels to the 4K display. Typically, most Macs produced after 2013 are capable of supporting this resolution, but if you’re unsure, you can check your Mac’s technical specifications for more information.

15. Strange Colors? Switch to a Different Profile

Perhaps you’ve managed to get your external display up and running, but the colors are noticeably different than how they appear on your Mac’s built-in screen.

Some external displays feature contrast and RGB (Red, Green, and Blue) buttons to tweak the display’s color profile. Please note that this feature does not work on newer macOS versions (Big Sur and Monterey).

If your external display doesn’t feature these buttons, then you can often fix color-related issues using macOS’s Display Calibrator Assistant:

  1. Navigate to “System Preferences -> Displays.”
  2. Locate “Color Profile” toward the bottom right.
External Monitor Not Working Color Profile
  1. Select “Calibrate … ” to launch macOS’s Display Calibrator Assistant.
External Monitor Not Working Calibrate
  1. Follow the on-screen instructions to calibrate your display.

Alternatively, you can try various color profiles to see whether any of these profiles are a better fit for your external display. To select a new profile, navigate to “System Preferences -> Displays -> Color,” then explore the various color profiles on the list.

Frequently Asked Questions

1. Will non-Apple adapters or incompatible adapters cause a display problem?

While it may seem easy to pick up dozens of different adapters on Amazon, they are not all created equal. The best move is to always go with a name brand and something that you verify is compatible – not just any $1.99 option. There are third-party adapters that will work, plenty of them in fact, but this is definitely an area to explore if you are having display problems.

2. Do the same tips apply if you are using an iPad as an external monitor?

In some cases, yes, as things like proper cables will still play a factor in overall troubleshooting tips. So, too, will basic tips like disconnecting and reconnecting and ensuring all necessary software updates have been performed. Beyond that, most of these tips are exclusive to monitors and not the iPad.

David Joz
David Joz

David is a freelance tech writer with over 15 years of experience in the tech industry. He loves all things Nintendo.

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