You can make a difference in the Apple Support Community!

When you sign up with your Apple Account, you can provide valuable feedback to other community members by upvoting helpful replies and User Tips.

Looks like no one’s replied in a while. To start the conversation again, simply ask a new question.

tjh421 Author

Level 1

5 points

third display won't detect on mac pro, using Catalina update

I recently updated my MacPro (late 2013) to Catalina. My three displays I had hooked up worked fine, then today I replaced a wire to one of the monitors so that I am using all thunderbolt to HDMI on all three monitors. Once I replaced the wire, one of my monitors will not detect.

I can use the two monitors, but the third will not detect. I can unplug one monitor and get the other two to work, I can change the thunderbolt ports on the MacPro and they all work, all ports work, all monitors work, all wires work, but the computer just won't detect the third monitor.

I went to System Preferences, displays, and under arrangement hit the option key to display the "detect displays" button, but nothing. I've reset the pram by rebooting and holding option control pr, but nothing. I've shut down and unplugged the MacPro and all the thunderbolt wires, but to no avail.

Posted on Jun 19, 2020 4:46 PM

Top-ranking reply

tjh421 Author

Level 1

5 points

Posted on Jun 20, 2020 8:41 AM

that explains why the three monitors worked when I was using the old DisplayPort cable with a thunderbolt adapter.

i switched back to the old display port connection and now all three monitors work again.

thank you.

View in context

third display won't detect on mac pro, using Catalina update

Similar questions