Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.

SparkFlash

macrumors 6502
Original poster
Feb 15, 2013
370
132
Michigan
On my 2018 15 MBP-TB, I can never quite figure out how to use two external monitors on my USB-C adapter. My adapter has 2 HDMI outputs and the closest I can get it to work is having them mirror each other. It does not recognize them as separate monitors.

What am I missing? Ive searched and gotten so much conflicting info that I am coming here for advice. Is it not possibe?

Thanks
 

Honza1

macrumors 6502a
Nov 30, 2013
937
437
US
This is a guess, but I think you need to use two usb-c ports in this case. Each monitor needs its own? Get usb-c to hdmi or better display port cable for each monitor - I found this working best for my 4k displays.
 

Stephen.R

Suspended
Nov 2, 2018
4,356
4,746
Thailand
What adapter do you have? If it’s USB-C (and not TB3) it likely only has the ability to run one display.

With a TB3 adapter you can run multiple 4K displays. Several companies sell their own branded version of essentially the same adapter that I use: https://eshop.macsales.com/item/OWC/TB3ADP2DP/

OWC also sell a dual HDMI version (looks almost identical), not entirely sure about other vendors on that point.
 

dwig

macrumors 6502a
Jan 4, 2015
905
447
Key West FL
macOS does not support dual independent monitors on USB, though it does support such on TB3. It is an OS limitation. Windows 10 does support the appropriate dual channel DisplayPort Alt mode on USB, hence those hubs with dual ports will usually note the difference in functionality. In order to get dual independent displays on a single wire using a Mac, you need to use a TB3 port and a TB3 hub or docking station.
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.