USB C to DisplayPort hub works with VGA but not HDMI

Question

I have a Cable Matters USB C to Dual 4K DisplayPort Hub and a MacBook Pro 2016 (No touchbar). I am using Windows on Bootcamp.

The hub works fine with a DisplayPort to VGA adaptor, but it doesn't work with a DisplayPort to HDMI adaptor or cable. I have tried the hub on both MacOS and Windows 10 but the external HDMI display detects power (an icon appears showing there is something connected) but does not detect any signal.

I have updated the graphics drivers, reinstalled the USB C drivers and reinstalled Windows but nothing worked. The hub and HDMI display work with a HP laptop with similar Intel integrated graphics.

Does it not work because the DisplayPort to HDMI is passive?

Answer 1

Yes, you'll need an active DisplayPort to HDMI adapter for this to work. A passive adapter does not work.

The reason this doesn't seem intuitive is that many DisplayPorts ports are of the "DisplayPort++" type (also called dual-mode). Those are able to automatically detect when used with HDMI, and then the port outputs a signal specifically for HDMI. The non-++ DisplayPort ports on your hub does not do that - and thus need an active adapter for converting the signal.

You can use an adapter such as this:

https://www.amazon.com/dp/B00EDT0072

It sounds like you've left out some part of the explanation on how you got it working with a HP laptop - as the same limitation should apply there.

Note: If you intend to connect two displays for extended desktop, this hub won't work. Connecting two seperate displays requires support of MST, which macOS does not offer. You'll need to use a Thunderbolt 3 adapter or dock instead.