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How to fix Mac detecting two monitors as one

Man using Mac with dual monitors

Imagine the excitement of upgrading your home office with an additional monitor for your Mac®, only to find that the new setup isn’t working as expected. Instead of a seamless dual-screen experience, you're left troubleshooting why the second monitor isn't being detected.

When your tech fails, we don’t. The experts at uBreakiFix® by Asurion turn tech trials into triumphs with quick solutions that keep your devices connected. Here’s what you can do about your Mac detecting two monitors as one.

Why is my Mac only recognizing one monitor?

When your Mac only recognizes one monitor instead of multiple displays, the issues can often be traced back to a few common causes:

  • Outdated software. If your macOS or relevant drivers aren't up to date, it might not support newer hardware or may have unresolved bugs affecting display functionality.
  • Improper cable connections. Loose or damaged cables can prevent a successful connection between your Mac and additional monitors. It is crucial to ensure all connections are secure and use high-quality, compatible cables.
  • Incorrect configuration settings. Sometimes, the display settings might not be configured correctly to extend the desktop to multiple screens. Checking these settings can often resolve the issue.
  • Hardware limitations. Some Mac models have limitations on how many and what type of monitors they can support simultaneously.
  • Faulty ports or hardware. The monitor itself, the ports on your Mac, or the graphics card could be faulty, requiring hardware repairs or replacements.

How to fix a Mac that’s only detecting one monitor

Expanding your digital workspace with additional monitors should expand your productivity, not your problems. Follow these steps when your Mac only recognizes one monitor.

Check the cable connections

First things first: ensure all cables are securely connected. Loose or faulty cables are common culprits behind display issues. Double-check each connection point between your Mac and your monitors. If any cables are worn or damaged, replacing them might instantly solve your problem.

Use Detect Displays feature

If your connections are secure but the issue persists, it's time to prompt your Mac to search for an external display manually. Follow these steps to try detecting external displays:

  1. Go to Apple Menu > System Preferences > Displays.
  2. Hold down the Option key and click the Detect Displays button.

Adjust the display settings

Adjusting your display settings on your Mac can help resolve monitor connection issues. You can help your Mac recognize and effectively use the connected monitor by tweaking resolution and arrangement settings.

  1. Click the Apple menu > System Settings > Displays.
  2. Scroll down and select the display you want to adjust.
  3. Arrange your display icons to match the physical setup of your monitors. Uncheck the 'Mirror Displays' option unless you want both screens to show the same content.

Update your software

Updating macOS can help fix compatibility issues with external monitors by applying the latest software updates, which often include bug fixes and enhancements for audio driver compatibility.

To update, go to the Apple menu > System Settings > General > Software Update, and install any available updates. If you don't have System Settings in the Apple menu, click System Preferences > Software Update.

Reset the NVRAM

Resetting your Mac's NVRAM, which stores settings like sound volume and display resolution, can resolve issues with external monitors not being recognized properly. This step often reestablishes correct monitor connections by clearing out old settings.

  1. Shut down your Mac.
  2. Turn it on, and immediately press and hold Option + Command + P + R for about 20 seconds.

This process resets your computer and the information it stores about external displays without jeopardizing your saved data.

Want to add your iPad to your external monitor set up? You can use our guide on using Apple® Sidecar to get it done.

If you've tried these steps and still need a little help, we're right around the corner. Schedule a repair at the nearest uBreakiFix® by Asurion store and our certified experts can get your device back up and running as soon as the same day.

*The Asurion® trademarks and logos are the property of Asurion, LLC. All rights reserved. All other trademarks are the property of their respective owners. Asurion is not affiliated with, sponsored by, or endorsed by any of the respective owners of the other trademarks appearing herein.*

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