Multiple monitors on 14inch M3Pro MacBook Pro

Closing the lid on most Apple Silicon Mac notebooks – including yours – has no effect on the number of supported external displays.

To date, only M3 MacBook Airs and M3 MacBook Pros with the 'base' M3 chip provide any support for reallocating resources from the built-in screen to drive another external one. The M3 MacBook Airs had it from the beginning – on the M3 MacBook Pros, the hardware was there, but the software to enable the feature was not, at first.

You could use a "workaround" product like a DisplayLInk-based adapter to attach a third display to your MBP. This would come with compromises for any display attached in that fashion - and you might not be able to stream video from DRM-infested movie and TV services to ANY of your displays as long as the "workaround" product was active. But you say that "My desire for three displays is a need for a LOT of text data (no graphics or photos) on screen at once while providing support for a multi day conference hosted mostly on Zoom."

If you go this route, you would probably want to

• Drive your two existing monitors using your Mac's first-class, hardware-accelerated video outputs
• Use the "workaround" only for the third monitor
• Put the Zoom conference window on one of the two monitors attached in a first-class way, since the contents of the Zoom video feed won't be as nearly as static as your text data
• Avoid using the "workaround" software when you're not using the third monitor. I think DisplayLink might run as an application (rather than as a kernel extension) these days, so that might be as easy as quitting out of – or not launching - that application.

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 can suffer from lagging. Just adding the DisplayLink Driver is not adequate to get a picture -- you need a DisplayLink "stunt-box" or a Dock that includes DisplayLink chips.

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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 (as one user put it) “without too many dropped frames".

If you are only doing program listings spreadsheets, stock quotes, and other slow to change data, DisplayLink can work for you, but requires you to make some strong compromises.

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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, Hardware-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 disabled 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.

With one minor exception, the same rules we learned for the M1 and M2 still apply to the M3 models. Display interfaces are generated deep inside the system on a chip. How many there are depends on the exact type of Processor:

M3 (plain) like the 13-in and 15-in supports up to ONE External fully hardware-accelerated external display. Except the M3 MacBook Air models with 13 or 15-in display, which can support a second external display instead of the built-in display when you close the cover on the built-in display.

M3 PRO processor supports up to Two fully hardware-accelerated external displays.

M3 MAX processor supports up to Four fully hardware-accelerated external displays.

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what work are you doing on these displays?

full motion video?

slow to change data like spreadsheets, stock quotes, program listings?

something else?

Re: “Except the M3 MacBook Air models with 13 or 15-in display, which can support a second external display instead of the built-in display when you close the cover on the built-in display.”

M3 MacBook Pros with plain M3 chips can now pull the same trick - if they are running the latest version of Sonoma.