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Home » How to Run Two or More External Monitors on M1–M4 MacBook Air – Perth Guide

How to Run Two or More External Monitors on M1–M4 MacBook Air – Perth Guide

Multiple External Monitors on M1–M4 MacBook Air: Perth How-To

Apple’s plain M-series laptops place strict limits on native external screens. The table below shows what each chip can do out of the box and when you need a USB graphics adaptor such as the Comsol COCM21HSM or a DisplayLink dock.

Native Limits vs Workarounds

Chip (base model) Native external-display limit When do you need USB graphics?
M1 / M2 1 external (lid open or closed) For a second or third screen
M3 1 external with lid open
2 externals with lid closed (clamshell)		 If you want lid open dual-screen or a third screen
M4 2 externals with lid open or closed If you want a third screen

Hardware Combos That Work

  • One extra monitor on any model: Dell WD19S or similar USB-C dock.
  • Two monitors on M1 / M2: WD19S (monitor A) + Comsol COCM21HSM (monitor B).
  • Two monitors on M3 lid closed: plug each monitor into a separate Mac USB-C port or use two basic adapters.
  • Two monitors on M3 lid open or three monitors on any model: WD19S + Comsol COCM21HSM.
  • Three monitors with one box: swap both for a Dell D6000 (DisplayLink) – 2 × 4K 60 Hz + 1 × 1080p 60 Hz.

Step-by-Step: WD19S + Comsol COCM21HSM

  1. Connect monitor A to the WD19S (DisplayPort or HDMI).
  2. Plug the Comsol adaptor into a USB-A port on the WD19S and connect monitor B to the 1080p HDMI socket (use the 4K socket if that monitor is 4K).
  3. macOS prompts to open InstantView. Install, then allow it under System Settings ▸ Privacy & Security ▸ Screen Recording.
  4. Open System Settings ▸ Displays. Set each display to Use as Separate Display and drag to arrange them.
  5. (Optional) Add a third screen by using the Comsol’s spare HDMI socket or upgrading to a Dell D6000.

Performance Notes

  • No HDR or adaptive sync on USB-graphics screens.
  • Small CPU load – fine for office work, coding, web, and streaming video.
  • Some protected streaming apps may refuse playback on virtual displays.

Where to Buy in Perth

The Comsol COCM21HSM adaptor is usually in stock at Officeworks Belmont, Osborne Park, and East Perth. Call first – most stores stock only a few units.

Need a Hand?

PcRiot offers fast onsite or remote setup across Perth. Book a session and get the screens you need without the hassle.