How to use dual monitors on a MacBook Pro with the M1 chip?

The MacBook Pro with the M1 chip supports only one external monitor.

MacBook Pro (13-inch, M1, 2020) - Technical Specifications

"Simultaneously supports full native resolution on the built-in display at millions of colors and:

One external display with up to 6K resolution at 60Hz"

Only the MacBook Pros with the M1 (or M2) Pro or Max chips support more than one external display.

The 2020 Apple-Silicon M1 13-in MacBook Pro and Air are extremely-capable entry-level computers. They can support the internal display AND an External display up to the previously unheard of size of the Apple 6K display at billions of colors. But only ONE in addition to the internal display.

This may not match the way older computers forced you to work, since older computers were not able to support a really large external display. But it is NOT a defect. The spec was available long before you could purchase the computer.

Fetching screen data is done by rasterizer/display-generator Hardware in the graphics subsystem. Once set up, data are fetched at that same interval again and again without additional intervention. The entire screen data MUST be completed within each screen refresh interval (often 1/60th second) or the screen will go partially or completely blank without the late or missing data. In addition, each one-pixel-tall Row must be fetched on a much tighter schedule within one row-time, or part of the row will be blank.

The MacBook Pro M1 memory features a "unified" memory design. Everything comes from that one memory array, with one memory access logic. Many devices are competing for access to the memory access logic, and screen refresh is especially urgent. In this M1 entry-level design, there is no more additional memory bandwidth to support more than the built-in display and one external display up to 6K in size. No additional rasterizer/display-generators can work correctly, because memory bandwidth is limited.

Executive summary: additional Hardware-accelerated display support can NOT be added to the entry-level 13-in M1 systems.

@spacehead777 - I'm using a 2020 MacBook Pro M1 and have been connecting 2 external LG 32-inch FreeSync displays using UGREEN Revodok Pro USB C docking station along with DisplayLink Manager software. 1st display connects to the HDMI port (HDMI to HDMI cable) and the 2nd display connects to the DisplayPort (DP to HDMI cable). You can not connect your displays using HDMI and HDMI or DP and DP ports simultaneously. One of your displays must be connected using DisplayPort for this to work. Download and install the DisplayLink Manager software and you'll have access to both the external displays along with your internal MacBook Pro display.

Cheers!

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.

————

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 listing and stock quotes and other slow to change data, DisplayLink can work for you, but requires you to make some strong compromises.

--------

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.

--------

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.

Grant I appreciate the technical insight that you've provided. However, the question posted was for a solution that would allow someone with a similar hardware configuration to be able to connect more than a single external monitor. Certainly, there are always higher end solutions better Macs/PCs with high end video cards as long as your budget can allow. From my personal experience with this setup using the UGREEN dock, I have not experienced the lag in video performance as you've indicated while using Final Cut Express on my MacBook Pro M1. I also stream YouTube TV in on my second display also with no lag. However, to be fair, I do have a 1GB up/down fiber optics as my home Internet and subscribe to 4K streaming service. Therefore, even though DisplayLink is a "fake" display, it still meets my needs with this MacBook Pro M1. Thank you again, for the in depth technical background and the limitations of the first generation M1 MacBook Pro.

<<. Therefore, even though DisplayLink is a "fake" display, it still meets my needs. >>

if we were all adequately informed by the folks selling this gear, and got what we expected in every case, I would not use such pejorative terms for DisplayLink displays. DisplayLink displays definitely have a place, provided you can live with the drawbacks.

if sounds like your work does not require video perfection, or using a mouse on that display, so that is a great place for a DisplayLink display.

santaslittlehelper wrote:

Grant I appreciate the technical insight that you've provided. However, the question posted was for a solution that would allow someone with a similar hardware configuration to be able to connect more than a single external monitor. Certainly, there are always higher end solutions better Macs/PCs with high end video cards as long as your budget can allow. From my personal experience with this setup using the UGREEN dock, I have not experienced the lag in video performance as you've indicated while using Final Cut Express on my MacBook Pro M1. I also stream YouTube TV in on my second display also with no lag. However, to be fair, I do have a 1GB up/down fiber optics as my home Internet and subscribe to 4K streaming service. Therefore, even though DisplayLink is a "fake" display, it still meets my needs with this MacBook Pro M1. Thank you again, for the in depth technical background and the limitations of the first generation M1 MacBook Pro.

Regardless of your experience and satisfaction with reduced display functionality, the M1 and M2 Macs support a single external display. You can add whatever devices you wish to add but doing so does not change the number of external displays supported. Adding a device to allow for the physical connection of additional displays does not change the computer capability.

just plug both in, should work