User profile for user: brett_larson
brett_larson Author
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MacBook Air (2020 M1) Issues Detecting and Utilizing Two External Display Monitors

I recently made the move from Windows 10 to Mac, and I love it. However, I am having difficulty getting my two external (Asus) monitors to work with my laptop. I purchased the CalDigit Thunderbolt 3 Mini Dock for additional ports, and I connected both monitors to the two HDMI ports. When I plug one HDMI cord in, that monitors work; however, both screens go blank if I try two. Additionally, sometimes the text gets garbled on the screen.


I tried different HDMI cords with no success. Additionally, I tried various sequences of steps of restarting the laptop, turning the monitors on and off, and plugging the HDMI cords into the adaptor and the adaptor to the laptop with no success. I am running OS Big Sur 11.1.


I tried similar steps with a Selore&S-Global USB-C Dual HDMI adaptor I used with my Windows 10 laptop. Unfortunately, I experienced the same results.


Any assistance or advice is greatly appreciated. Thank you!

Posted on Dec 19, 2020 4:45 PM

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User profile for user: neuroanatomist
neuroanatomist
User level: Level 9
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Posted on Dec 19, 2020 5:49 PM

The M1 Mac notebooks support only one external display, at up to 6K resolution.


The only workaround is a dock that supports DisplayLink, but that’s a rather hack solution that lacks hardware acceleration and is subject to being borked by macOS updates.

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User profile for user: neuroanatomist
neuroanatomist
User level: Level 9
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Dec 19, 2020 5:49 PM in response to brett_larson

The M1 Mac notebooks support only one external display, at up to 6K resolution.


The only workaround is a dock that supports DisplayLink, but that’s a rather hack solution that lacks hardware acceleration and is subject to being borked by macOS updates.

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User profile for user: brett_larson
brett_larson Author
User level: Level 1
8 points

Dec 22, 2020 4:37 PM in response to neuroanatomist

Thanks so much for the great information! I was unaware of this limitation in external monitors. I suppose now is a good time to look at upgrading to a larger monitor and toss the dual monitor setup (assuming Apple isn't planning on making updates to support dual monitors). Thanks again! I appreciate the information.

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User profile for user: w1111amh
w1111amh
User level: Level 1
4 points

Jan 30, 2021 5:09 PM in response to brett_larson

I have a similar issue with a MacBook Pro M1, my setup is slightly different, but i get similar and more alarming results. I am running an LGUM7300PUA and a Older Samsung 24" HD with HDMI connections. I used this setup on my MacBoo Pro 2012 i7, no problem although the video card wasn't the best fit with the newer TV monitor it worked enough. After getting the new MacBook Pro I knew I was going to need a dock solution. and I couldn't make up my mind which one, i finally ordered the CalDigit minidock. In the meantime I found I could run the LG via airplay and it worked well.


However, when I got the CalDigit Minidock I of course tried to run the two external monitors and of course as advertised it didn't work. However I was able to get one the SS running through the CDMD and the third LG via airplay. Thats when I realized the resolution on the SS through the CDMD was poor, and same throughs LG if i ran it as the sole monitor. Running through Airplay it was clear and through the CalDigit muddled and text was blurry. i then started to run the SS through CDMD and the LG through airplay and while trying to figure out the resolution, my MBP just started to reboot on its own. Particularly if I ran my Trading Software TOS, it got so bad that as soon as it rebooted and everything loaded it would automatically reset again. Its gotten so bad I had to unplug the CDMD from the setup and go back to how I was using it. Was wondering if anyone else could replicate this issue and tell me if it is the setup CDMD, or the MBP or running TOS if they encountered any issues like that. Of course the CS for CDMD is closed and Apple had no answers so looking to the great void for answers. Thanks in advance.

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MacBook Air (2020 M1) Issues Detecting and Utilizing Two External Display Monitors

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