only one of my external display work ( macbook pro M3 )

souellette wrote:

Is there a workaround ?

There are workarounds – but they may involve significant compromises. There is no hub, dock, or adapter that can give you additional first-class, hardware-supported display outputs.

The workaround products might not be suitable for applications like video editing and playing high-end games, where there is going to be a lot of quickly-changing video content. They might be subject to artifacts and lags. They may not play well with DRM-infested video (such as video from a commercial TV/movie streaming service). If updates to macOS break the software that makes them work, you'll be reliant on a third party to fix it.

One technology commonly found in these products is DisplayLink, from Synaptics. ("DisplayLink" is a different thing from the "DisplayPort" video interface standard.).

https://www.synaptics.com/products/displaylink-graphics

https://support.displaylink.com/

Two vendors that make DisplayLink-based adapters are Other World Computing and SonnetTech.

Other World Computing - OWC USB-C Dual HDMI 4K Display Adapter with DisplayLink

SonnetTech – DisplayLink Dual HDMI Adapter for M Series Macs

SonnetTech – DisplayLink Dual DisplayPort Adapter for M Series Macs

What processor does your MacBook Pro have?

The models with M3 Pro and M3 Max chips support two or more external displays. The ones with base M3 chips support just a single external display.

 > About This Mac may reveal which chip you have. Also, if I remember correctly, the M3 models have only two USB-C (Thunderbolt) ports, whereas the M3 Pro and M3 Max models have three.

souellette wrote:

I have the Apple M3... this is so annoying how come it doesnt support 2 displays.

MacBook Pro (14-inch, M3, Nov 2023) - Technical Specifications

You'll have to ask Apple "why" they designed the chips this way … but the short answer seems to be that it is a hardware limitation of the main processor chip (System on Chip).

Going up a processor line to 'Pro', 'Max' and 'Ultra' seems to have a strong influence not just on the number of CPU cores and GPU cores, but on things like how much RAM you can order; how many multi-purpose USB-C / Thunderbolt ports you get, and the maximum number of displays your Mac can drive.

Every Mac to date that uses a 'base' M1, M2, or M3 chip has Technical Specifications consistent with the theory that the chip supports at most two displays – where any built-in iMac or notebook display counts as one of the two. Thus all Mac notebooks using the 'base' M1, M2, and M3 chips support only one external display. The M1 and M2 Mac minis support up to two displays (since there's no built-in display to use up an output); and the M2 Mac mini has more flexibility in the the way you can pick those two displays.