According to the FAQ for the CalDigit Thunderbolt 3 Mini Dock, two different monitors can be connected in extend mode through the single USB-C port. How is this possible if MST is not supported?

Why can one not do the same thing with other USB-C hubs like this one? It says in their FAQ that one cannot connect two external displays in extend mode on mac because of lack of support of MST.

1 Answer 1


The clue is in the name: Thunderbolt and USB are two different things, even though they both use the same plug and socket.

USB C offers some of the capabilities - video signal, power transmission, data; but Thunderbolt provides a greater range of data travelling down the same cable.

The Thunderbolt Dock has 2 HDMI ports, which can provide two separate video outputs. The USB hub has one HDMI port.

  • Is the problem with the USB-C hub that it is USB-C and not Thunderbolt 3, or is it that it has a mini-display port instead of the second HDMI port, or both? Thank you for your help.
    – joshLor
    Commented Jun 7, 2020 at 10:08
  • Yes, it's the nature of USB vs TB. I suspect you can use either video port but not both via USB.
    – benwiggy
    Commented Jun 7, 2020 at 10:29

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .