Dual Displays on Mac Mini M1 - NOT WORKING :(

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Level 1

10 points

Dual Displays on Mac Mini M1 - NOT WORKING :(

Apple Community,

I got have an interesting case for you all to marinate on.

I got the M1 MacMini Tuesday this week. I hooked up my left monitor (LG 32QK500-C) (32" LED monitor) and my right monitor a 27" ASUS curved monitor.

The left monitor (32" LG LED) is connected to the HDMI 2.0 port at 2560 x 1440.

The right monitor (27" ASUS Curved monitor) is connected via a HDMI to USB-C at 1920x1080 (the max resolution for this monitor).

On the above configuration. Everything worked perfectly.

On Friday 11/20, I received a second 32" LG (same model as mentioned above).

My intention was to replace the 27" curved monitor with the 32LG so both of them are exactly the same.

Once I swapped out my monitor with the new monitor, both displays went blank.

I called Apple support, and they had no fixes.

I went to Bestbuy yesterday and picked up a DisplayPort to USB-C cable to see if a different link might work, nope.

If I just leave my left monitor plugged in to the HDMI 2.0 port, monitor works.

If I plug any HDMI to USB-C or DisplayPort to USB-C on either of the two Thunderbolt ports, I NEVER get a dual display.

Here is what is really weird, I can remove the left monitor plugged into the HDMI 2.0 port, and my left monitor starts working.

Apple Support thought this might be a BigSur software issue. I have an open case with them that they have submitted to engineering.

Anybody getting the same issue, anybody have any fixes??

Thank you,

Jason

Mac mini 2018 or later

Posted on Nov 22, 2020 11:35 AM

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Answer 1

Miznalf

Level 1

9 points

Dec 1, 2020 9:20 AM in response to bigjstl

I'm having the same issue with my HP 24F monitors, both running at 60 Hz. One is plugged in via brand new 4K HDMI and the other with the Apple HDMI/USB-C adapter. All brand new and up-to-date cables. Both monitors work perfectly on their own, but the moment you plug both in, the screens go blank and the Mac eventually restarts. At boot, the status bar won't go past maybe 1/3 of the way, and then just keeps rebooting until I unplug one of the monitors.

I've tried the following troubleshooting:

Replaced/checked all the cables and adapters.
Did various standard "restart/reset" troubleshooting with the Mac itself, by direction of Apple support.
Did a complete wipe of the Mac and set it back up using Time Machine backup.

What's even more interesting is that if I go into Recovery Mode, both monitors work. And when I was going through the reset process, and using Time Machine to do the recovery, the monitors also both worked all the way up to the point where the Time Machine recovery was almost done. But once the Time Machine recovery finished, the problem occurred again.

I have a case open with Apple and have not called them back. I don't have confidence they have a fix for this at the moment. It's definitely NOT hardware related.

Anyone else?

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Answer 2

bigjstl Author

Level 1

10 points

Dec 1, 2020 1:09 PM in response to Miznalf

Thank you, Miznalf. I ended up doing a return. I still had my 2018 MacMini (which there was nothing wrong with it) and put it back in service. My 2018 MacMini was the dark grey one so it looks cooler. :)

I couldn't even get the new M1 MacMini I purchased to finish re-installing. I was one of those users that was having issues with that also.

I'm an early adopter, but the M1 MacMini is definitely early early adoption. Hopefully Gen2 will have more flexible video output options.

Cheers - J

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Answer 3

Dec 1, 2020 1:24 PM in response to Miznalf

I have a couple 32" 4K monitors - same issue when trying to use them. If I use either one, USB-C or HDMI, it works. If I use one and put the other on a different model/size monitor (34" wide with a smaller resolution), it works fine. Just if I try to use two 4k monitors, both screens go blank and I have to reboot the mini and disconnect one of the monitors to get it working again.

I had to use the HDMI port to get the thing loaded the first time with a single monitor.

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Answer 4

Miznalf

Level 1

9 points

Dec 14, 2020 3:50 PM in response to ericfromraleigh

Hey everyone, I just installed the Big Sur 11.1 upgrade that was release today and so far (knock on wood) I am able to get BOTH monitors working. I can't believe it.

My bluetooth keyboard also reconnected after reboot on its own, which was another issue I was having.

It's a great day. Haha.

[Edited by Moderator]

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Answer 5

Feb 4, 2021 8:21 AM in response to bigjstl

I have a very similar issue. Got the new Mac mini M1 last week. Hooked up two monitors. One is a Lenovo 24Q-20 that's about 3 years old. The other is an ASUS MX25AQ. Both are 2560X1440. One via HDMI port. The other via thunderbolt to hdmi, or thunderbolt to displayport- both work fine. These two monitors work fine together.

Bought another ASUS MX25AQ so I could match with the other and give me wife the Lenovo. The two ASUS monitors will not run together, and in fact crashes the Mac Mini (sent all reports to Apple)

I am puzzled.