Macbook Pro External Monitor Flashes On and Off – Solved

People using MacBook pro with external screens or monitors often face the issue of flickering. You can also face this issue if you have a multi-screen setup enabled with DisplayLink.

Even if you use MacBook Air and M1 Mac Mini, and when you connect it with an external display, you can face this issue.

MacBook Pros, especially MacBook Pro 18 and 19, having discrete graphics, often have a flickering screen issue.

Other than your MacBook Pro external monitor flashes on and off, you can also face a display with white noise when your Mac has woken from sleep, or your laptop display won’t wake up from sleep, and the screen stays black, or white noise when you turn on your MacBook after it slept or turned off.

This condition can be frustrating, but don’t worry; I’m sharing some possible solutions for the flickering issue.

Macbook Pro External Monitor Flashes On and Off – Solutions

Lets discuss the macbook pro external monitor flashes on & off issue reasons and solutions in detail.

1. Turning off Automatic Graphics Switching

When you solve this flickering issue, you have to keep one root cause of this issue in mind. When you connect your MacBook to an external monitor, automatic switching between graphics systems remains on.

So if you want to avoid this issue, you have to turn this feature off.

By the below steps, you can do this yourself:

  1. Go to Apple Menu and then from there select “Systems Preferences.”
  2. After selecting the “System Preferences,” you will see options. From these options, select the “Energy Saver.”
  3. Then you will see another menu, and from here, you will have to click the checkbox to deselect the automatic graphics switching.

Important Note: 

Don’t worry if the automatic graphics switching doesn’t appear because it indicates that your system has a singular graphics system.

If you want to confirm that go to the Apple menu and click on “About this Mac.” After that, click on “System Report” from the given options and select the Graphics/Displays option.

You will see your MacBook’s graphics system under the video card section on the left side when you click this option.

2. Shutting off your monitor before connecting it to your MacBook

Another hack can help you avoid this problem, as most people have found this helpful. When you connect an external monitor with your MacBook Pro, shut your monitor off and connect your laptop to this external display.

When your MacBook has recognized it, then turn it on. Sometimes, you have to repeat it twice.

Alternatively, you can also do it in this way.

  • Connect your monitor to your MacBook when your laptop is up and running.
  • After this, disconnect the power source of your monitor only from the power outlet and wait for 10 to 15 seconds.
  • Then, connect the power source plug of your monitor back into the power outlet.
  • After your monitor is on, go to the displays area of system preferences, and once you set “Default for Display” under the Displays section of System Preferences, it should show “Looks like 1920 x 1080”.

Important Note: 

It is not recommended to disconnect the USB-C cable (or dongle) from your Mac. Please do not remove it.

3. Disconnect and reconnect display/HDMI cable

If your external monitor is flashing on and off or showing white noise, you can disconnect and reconnect the display cable while your laptop is powered on.

As a result, MacBook will refresh its display, and the external display will also be refreshed, and the problem will be resolved.

Important note:

The issue will not be resolved if you remove, disconnect and reconnect the USB-C dongle adapter; you have to disconnect and reconnect the HDMI cable to fix the flickering issue.

4. Switch to a different cable or connection method

There are times when an afflicted display works fine with one type of cable but not another. An issue may arise with a particular connection method but not with another method.

A cheap USB-C to HDMI dongle may not work for some users, but a higher quality USB-C to HDMI adapter may work, or if HDMI does not work, then perhaps a USB-C to DisplayPort cable will work.

A Warky USB-C to DisplayPort cable compatible with my external display completely fixed my flickering and noisy external display on an M1 MacBook Pro.

Anecdotal, yet something to consider, especially if you’re getting frustrated with unplugging and plugging back in the cable.

5. Mac Rebooting

Occasionally, restarting the Mac also appears to fix the flickering display issue, but it can be annoying and should not be required for most Mac users.

Consider instead disconnecting and reconnecting the cable using the methods discussed above. If the display doesn’t wake up at all, restarting the M1 Mac seems to temporarily fix the problem (at least until it is put to sleep again).

6. Disable External Display Sleep

Display flickering is also prevented by stopping the display from going to sleep. By following these few ways, you can do this:

  • Turn off External Display Sleeping on Mac
  • Go to the * Apple menu and select System Preferences.
  • “Battery” for MacBook Air, MacBook Pro, or “Energy Saver” for Mac Mini, iMac
  • Choose “Power Adapter,” then drag the slider for “Turn Display Off After…” to “Never” on Macbooks M1.

Reasons for External Monitor Flashing

Several MacBook Pro models from 2018 and 2019 feature two graphics systems to offer you the highest level of performance when you are using them.

For optimal graphic performance, the software switches between two graphics processors, namely a discrete graphics processor and an integrated graphics processor.

The automatic graphics switching function is enabled by default on a MacBook Pro. The flickering effect is caused by the switching between graphics systems when your device is connected to a USB-A or USB-C docking station that uses DisplayLink.

Kensington docking stations leveraging DisplayLink technology are not affected by this issue.

Frequently Asked Questions (FAQs)

Why is my external monitor flashing on and off?

An incompatible application or display driver is the most common cause of screen flickering in Windows 10. Test if Task Manager flickers to determine whether a display driver or an application causes the issue.

Why is my Mac screen flashing on and off?

If you own a MacBook Pro, you may have experienced screen flickering when the Energy Saver function is misconfigured.

You can resolve this issue by disabling “Automatic graphics switching,” which will prevent Mac from switching between different graphic chips.

How do I fix my external monitor flickering?

What to do if your monitor is flickering:

  • Check your monitor cable. Monitor DVI cables come with screws at both ends to keep them secured, but they are not universally used.
  • Make sure the power supply is working. Verify the cable is secured at both ends.
  • Make sure the display settings are correct.
  • Make sure your graphics card is working.
  • Also, check the monitor.

Leave a Comment