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MacBook Pro M1 - External Display Issues (Can't connect 2 monitors)

Hello -


Have a brand new MacBook Pro M1 and can't connect two monitors at once. Both are pretty much brand new 4k LG 27' monitors. Both work when I plug them in but just not at the same time. If they are both plugged in two both USB C ports it will default to one of them. Not sure what to do. I did buy the 3 port adapter and tried HDMI, etc. and still no luck. Hoping this can be resolved without having to schedule an appointment. Any help would be appreciated.


Thank,


Kevin

MacBook Pro 13″, macOS 11.0

Posted on Dec 5, 2020 8:05 AM

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Question marked as Top-ranking reply

Posted on Dec 5, 2020 8:27 AM

Google DisplayLink. External hardware, non-hardware accelerated displays and macOS updates can break the drivers. But sure, it ‘works’.


The M1 notebooks support one external display. Always good to review the specs of something before buying it.

5 replies

Dec 5, 2020 10:38 AM in response to 45patriots12

DisplayLink technology creates a "fake" display buffer in RAM, sends the data out over a slower interface to a stunt box with DisplayLink custom chips that put that data back onto a "legacy" interface. It is not a true "accelerated" display, and it suffers from lagging.


It may be acceptable for a second display showing slow-to-change data such as computer program listings, stock quotes, or spreadsheets, but NOT for full motion Video, not for Video editing, and absolutely not for gaming. Mouse-tracking on that display can lag, and can make you feel queasy.


In a pinch, it may even play Internet videos without (as one user put it) "too many dropped frames".


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It is really nice to know that you can use a DisplayLink display if you MUST have an additional display for some of the types of data I mentioned. But that is NOT the same as the computer supporting a second, built-in, accelerated display.


These displays depend on DisplayLink software, and are at the whim of Apple when they make MacOS changes. There have been cases where MacOS changes completely Borked DisplayLink software, and it took some time for them to recover.


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I think the Big Surprise for a lot of Hub/Dock buyers is that they thought they were getting a "real" display, but actually got a DisplayLink "fake" Display. If you got what you expected in every case, I would not use such pejorative terms to describe DisplayLink.


MacBook Pro M1 - External Display Issues (Can't connect 2 monitors)

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