Fixing M1 Mac External Display Issues (Flickering Screen, White Noise, Black Screen, etc)

Jul 10, 2021 - 15 Comments

Fix M1 Mac external display issues like flickering and white noise

Some M1 MacBook Pro, M1 MacBook Air, and M1 Mac Mini users have discovered display issues when using an external display connected to their M1 Mac. Typically the M1 Mac external display issues are either a flickering display, a display that won’t wake from sleep and where the screen stays black, or a white noise display visible after the Mac has woken from sleep, or after the display has slept or turned off and is attempted to be used by the Mac again.

If you’re experiencing external display issues with an M1 Mac, read on to learn about possible fixes and workarounds to the display flickering, white noise showing, black screens that won’t wake, or other similar issues.

This issue seems to exist regardless of which dongles, display connectors and adapters, or display cables are used, and whether or not it’s a compatibility issue between the M1 Mac series and certain external displays, a bug with macOS that has yet to be resolved, or some other problem, is not yet clear. Some users have reported success with using a USB-C to HDMI or USB-C to DisplayPort cable with the M1 Mac, instead of a dongle or adapter, but that does not resolve the problem for everyone.

How to Fix External Display Issues with M1 Mac

There are a few fixes and workarounds to external display issues with the M1 Macs, here’s what you can try if you are experiencing these problems:

Disconnect and reconnect display cable

If the external screen is flickering or displaying white noise, you can try to disconnect and reconnect the cable while the Mac is powered on.

This will cause the M1 Mac to refresh its own display, as well as the external display, which typically resolves the problem immediately.

Variation: Disconnect/Reconnect display cable from dongle (not from Mac USB-C port)

For my own M1 MacBook Pro, simply disconnecting and reconnecting the USB-C dongle adapter from the Mac does not resolve the display flickering or white noise issue. Instead, I’ve found disconnecting and reconnecting the HDMI cable from the USB-C dongle adapter itself works.

Rebooting the Mac

Rebooting the Mac also appears to often fix the display flickering problem, but this is annoying and should not be necessary for most Mac users. Instead, try the approaches discussed above with disconnecting and reconnecting the cable.

If the display won’t wake at all, forced restarting the M1 Mac seems to temporarily fix the issue (until it is put to sleep again, anyway).

Workaround: Disable Display Sleep

Preventing the display from going to sleep also prevents the display flickering problem. You can do this a few different ways:

Completely Disable External Display Sleeping on Mac

  1. Open System Preferences from the  Apple menu
  2. Choose “Battery” (M1 MacBook Pro, M1 MacBook Air), or “Energy Saver” (M1 Mac Mini, iMac)
  3. M1 Mac laptops choose “Power Adapter”, and then drag the slider for “Turn Display Off After…” to “Never”

Temporarily Prevent Display Sleep with a Hot Corner

Setting up a Hot Corner and choosing “Prevent Sleep” as the Hot Corner configuration, then remembering to throw the mouse cursor into that corner, will prevent sleep when used.

Install MacOS Software Updates when available

Though this issue persists with modern macOS versions (including macOS Big Sur 11.4, macOS Big Sur 11.5, and macOS Monterey for some users), installing the latest available macOS system software updates may resolve the problem eventually, particularly if it’s a bug that Apple has fixed.

You can update macOS system software through  Apple menu > System Preferences > Software Update.

A previous issue with the M1 Mac Mini having issues with displays not waking from sleep was apparently fixed with macOS Big Sur 11.3, but some users still experience the problem with later macOS versions, or variations of the issue (flickering screens, white noise, monitor stuck on black, etc), and with other M1 Mac models.

Try a Different Cable or Connection Method

Sometimes a particular display may have issues with one cable, but not another. Or sometimes a particular connection method may have problems, but another does not.

For example, some users may have problems with a cheap USB-C to HDMI dongle, but find that another higher quality USB-C to HDMI adapter may work fine, or if HDMI is not working then a USB-C to DisplayPort cable may work.

I was able to completely fix my flickering external display and noisy external display on a M1 MacBook Pro by switching from HDMI with a dongle to a Warky USB-C to DisplayPort cable that’s compatible with my external display. Anecdotal, but it’s something to consider, especially if the temporary fixes like unplugging and plugging the cable back in are getting to be annoying.

Miscellaneous Solutions to External Monitor Issues with M1 Macs

Mixed reports have also mentioned the following can be helpful:

“My M1 Mac works with external display fine, but the refresh rate is too low”

Some M1 Mac users also have discovered the refresh rate available used by an external display is 30hz, rather than the smoother 60hz, 120hz, 144hz, or higher options.

Certain HDMI cables, adapters, and dongles may be the reason the display is not showing 60hz or greater available as an option.

However, if you know the display cables are working with another device at 60hz, you can typically manually change the refresh rate on a Mac display with these instructions. You can also check refresh rate in use on the display as discussed here. A 30hz refresh rate is usually fairly obvious and not subtle, as the mouse cursor is typically choppy, as are dragging windows around on screen, and playing games or watching movies is choppy too.

Do you have display issues with external screens and your M1 Mac? What are the problems you are having, and how did you resolve them? Did you find another solution not mentioned here? Share with us your experiences, tips, and suggestions in the comments.

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Posted by: Paul Horowitz in Mac OS, Tips & Tricks, Troubleshooting

15 Comments

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  1. Travis Reed says:

    I just solved a similar issue with my setup by disabling my external monitor’s (in my case a Sony TV) ability to control the device through HDMI. Immediately fixed it. Idk if this helps but I spent hours trying so maybe it will be the fix for someone else.

  2. Ulfar Erlingsson says:

    Reducing refresh rate of external monitors also worked for me.

  3. Frank D says:

    Finally found a solution (at least for me) reduced the refresh rate and no issues in two days. It also stopped the arbitrary reboots….come on Apple this is really sad.

  4. Chris K says:

    I just purchased a new M1 Mac Mini to use for presentations. The HDMI to my main display is fine, but when I hit the thunderbolt output via dongle to a BlackMagic MicroConverter to SDI, the other end at my projector gives me a second display for a few seconds, then starts flickering, loses sync, goes black, then back on again… So annoying… If I connect a regular computer display to the same thunderbolt-dongle-hdmi, then it’s fine… It’s only when its going to my presentation switcher or to a converter then a projector… My other MacBookPro 13″ (bigsur) works just fine….

    • JL says:

      I have the same setup and having the same problem. Have you had any luck solving it? My older iMac works fine. New 2021 iMac with M1 doesn’t.

  5. John says:

    I’m going to return my Mac M1 mini. I’m trying to use the HDMI output to drive a 4K monitor. I know there’s nothing wrong with my cable as I use it in the same configuration with my dell laptop plugged into a dell docking station without issue. With the Mac mini M1 I constantly get flickering with HDMI.

    This is unacceptable from Apple. This product is not ready for real world use. As to why Apple wouldn’t release a product that has two thunderbolt ports but does not allow you to use both to drive two monitors unfathomable.

  6. np says:

    I switched my display refresh rate from 144 to 120 and it fixed it for me.

  7. Nicholas McDonough says:

    I bought a new cable HDMI to HDMI instead of HDMU to DVI. No Change. What’s odd is that during the daytime it’s not really an issue except when the screensaver activates.

    I’m now on 4th advisor as 1st ghosted me when I had the gall to question her approach.

    I find Apple advisors totally unhelpful with a propensity for conjecture. It seems the quality of support has eroded just like the software.

    What do people need to do? Bring a class action suit? It’s absurd.

  8. Chas says:

    Very sad that Mac Mini M1 running Big Sur 11.5, won’t run a second monitor via HDMI without flickering and sporadically coming on and off! How many upgrades are going to be issued before this flaw is fixed. I have tried every suggested remedy posted on the internet. Nothing works! It is up to Apple to fix this. I am very very very disappointed in Apple.

    • Paul says:

      Chas, I had the same issue with a flickering external display connected with HDMI to an M1 MacBook Pro, and the only way I was able to stop the second monitor from flickering was to switch from using HDMI to DisplayPort.

      Not all monitors offer other port options, but if yours does, it may be something to consider changing the cable.

      Keep us updated on what you discover, or what works for you.

  9. JohnIL says:

    I never had a single issue with my LG UD58 on my Intel Mac mini. Now that I traded in that for a M1 Mac mini I can’t seem to get a solid connection with Thunderbolt to DisplayPort. I have to use HDMI to HDMI in order to get anything stable. Seems odd that were months into M1 Mac’s and MaCOS 11 and still haven’t completely resolved issues with what is assumed are standard video output connections. I know some have zero issues but in reality most if not all should not have issues using proper cables and connections. These are standards that should just work.

  10. Ramius says:

    MacMini 2018 with Big Sur, same problem here. I turn off my display and turn it on again, it works, annoyed though.

    • Paul says:

      Have you tried using a different cable, if the display supports it? My issue went away completely when I switched away from HDMI (which works fine on other Macs with the same display) to DisplayPort.

  11. kk says:

    The Mac mini Late 2012 has the blank screen issue with external display, it never got fixes by Apple.

  12. David Bartram says:

    I have had this problem several times with my M1 MacBook Air. I changed cables and the HDMI port on my external display. The problem has continued to intermittently occur, although not very often.

    A symptom not mentioned in the article is that the display does not just contain on window, but half of one and half of another.

    Thanks for the article, it’s good to know it’s not just me.

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