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Mac Freezes When Connecting an External Monitor (Causes and Fixes)

As an owner of a Mac, I know how frustrating it can be when it freezes up when connecting an external monitor. I recently experienced this issue myself and spent some time researching and testing different solutions. Today, I’m here to share with you the solutions I discovered and the steps I took to fix the problem. In this blog post, I will discuss the possible causes of Mac freezing when connecting an external monitor and the various fixes that are available.

The reason why Mac freezes when connecting an external monitor is problematic adapter connections, especially if you’re using an average quality Mini DP to HDMI adapter. However, some users found other solutions to fix the problem, such as unchecking the “Power Nap” setting or switching to other macOS versions that didn’t have this problem.

If you want to find out more about this issue as well as the solutions that you can try to get it fixed, keep on reading this guide!

4 Reasons Why Mac Freezes When You Connect an External Monitor and How to Solve Them

There are several reasons why your Mac freezes as soon as you connect to external monitors. Here’s a quick look at all the possible causes:

1. Using a Passive Mini DisplayPort to HDMI Adapter

Although you might think that all Mini DisplayPort to HDMI adapters out there are basically the same, there’s a major difference between some of them.

For instance, if you’re using a passive adapter instead of an active one, your macOS is most likely going to freeze. 

The problem here is that passive adapters will simply take the same signal from a Mini DisplayPort and configure it directly into HDMI. 

While this works with many devices, it doesn’t work with macOS because the signals are of different voltages (DisplayPort is 3 volts while HDMI is 5 volts) and Display lacks the clock signal that HDMI has.

Solution 1: Switch to an Active Mini DisplayPort to HDMI Adapter 

Check your Mini DisplayPort to see if yours is passive, which you can find on the product’s label. If yours is passive, you should consider switching to an active one like Cable Matters Active Mini DisplayPort to HDMI Adapter.

Solution 2: Switch to Mini DisplayPort to DVI Adapter

Alternatively, you can try a Mini DisplayPort to DVI adapter, which is a cheaper alternative and works with external monitors with DVI ports without problems.

2. The Automatic Graphics Switching Needs Adjustment 

Since the problem happens only when connected to external monitors, it is seemingly caused by a conflict between the discrete graphics chip and the integrated graphics chip. For that reason, if you reset the state of discrete graphic drivers, the problem should go away.

Solution: Turn the Automatic Graphics Switching Off and On Again

To do that, all you need to do is to head to System Preferences and select the “Energy Saver” tab. 

There, you should be able to switch the “Automatic Graphics Switching” off and then turn it back on again, which solves the problem for most users.

3. Problems with Your Current macOS Version

Although this problem is quite common and on many different types of MacBooks, not everyone is actually suffering from it, so it must have something to do with the current version of macOS you have installed on your MacBook.

Solution 1:  Update to the Latest macOS Version

One of the easiest solutions to this problem is to simply upgrade your MacBook to the latest stable version of macOS, which solves the problem for a lot of people.

Solution 2: Revert Back to a Stable MacOS Version Where It Used to Work

Although updating works for some users, others already have the latest macOS version and still have it. 

In that case, you might want to consider reverting back to EL Capitan OS. According to many users who suffer from the problem, this solved the problem completely.

4. Your Macbook is Set to Sleep When the Display is Off

Lastly, some users found that the freezing issue is caused because of how they set up their MacBooks. 

This includes settings like Power Nap and how the device reacts when the display is off. If the mac freezes only when you shut off the lid or when the screen is off, this might be the culprit in your case.

Solution: Uncheck the “Power Nap” Setting

To uncheck the Power Nap setting, you should choose the Apple menu, then System Settings. There, select the Energy Saver tab from the sidebar, then tap the “Power Nap” option to turn it off.

Wrap Up

As you can see, there are several reasons why Macbooks freeze while connecting to an external monitor. 

While the exact reason varies from one user to another, there are various solutions that you can try in order to solve this problem, such as buying Apple’s Mini DisplayPort adapters, switching to DVI adapters, unchecking Power Nap settings, and switching to other macOS versions that don’t have the problem.

If all else fails, the only thing that is left to do is to contact Apple’s customer support or send your Macbook to get checked for any possible hardware problems in the ports themselves.