Holding the option check changes the Gather Windows button in the bottom right into Detect Displays. This detection can be triggered manually. Sometimes the displays will be discovered automatically, but not always. With all the adapters setup and the displays connected and powered on, open the MacBook. I could not reliably reproduce the latter case. The second display either wouldn’t be recognized, or it would work perfectly fine for a few seconds and then go black while still be recognized as an ‘active’ display. Not having one display per port caused issues when I added a KVM switch. This only worked when directly connected to the displays. I had one display driven connected to the hub’s HDMI port and the other to the USB-C to HDMI cable, also connected to the hub. Originally I had both displays going through my hub which uses two MacBook USB-C ports. Using an adapter that plugs into multiple MacBook USB-C ports should also only have one display attached to it. When connecting everything, the key is to only have one display output per MacBook port. For the second display I bought a USB-C to HDMI cable. It provides a single HDMI port for one displays, two USB-A slots (keyboard and mouse or KVM), plus USB-C slots for a better price than the Apple alternative.

I chose a SIIG hub that connects to the MacBook with two USB-C ports. Adapters are needed to support HDMI output. Supporting Multiple HDMI Outputs On MacBook This matters for all computers, but seems to be especially relevant in the Mac ecosystem.

Sweetysun two port dual monitor KVM switchīe aware that the cables you use must be able to support the bare minimum MacBook specifications.

SIIG Dual USB-C Hub adapter with HDMI port.

MacBook Pro running macOS Catalina 10.15.4.

Both directly connecting the MacBook to the external displays and using a KVM switch are covered.ĭue to some quirks with Apple hardware I had to go through a few setups myself before I got it all working properly. This article covers how to attach two or more displays to a MacBook, specifically a MacBook Pro.

Hdmi not working mac settings