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Mac mini connection to external display via USB-C/HDMI

Every few days I find myself having to re-wire my desk to swap out my Thunderbolt-DisplayPort cable from my Mac mini (2018 baseline) to it's Samsung 4K monitor to an HDMI cable.


Occasionally, on startup the Mac will fail to connect to the monitor, leaving it with just a blank-black screen, when using Thunderbolt-DisplayPort. If I swap out the cable for a HDMI to HDMI cable, it works, albeit at a lower quality/resolution (it's also dimmer for some reason).


After another few days, I get frustrated with the HDMI cable quality and swap back to Thunderbolt-DisplayPort and it works fine, but just for a few days, and then we start all over again. Any ideas what might be causing this?


Just to cover a few things:

  • the screen connection ONLY fails on startup, ever on wake from sleep, or during a session.
  • I've tried using all 4 Thunderbolt ports on the back of the Mac mini.
  • I always ensure the monitor is set to the right input.
  • I've tried disconnecting all other peripherals, such as Hard Drives, USB mouse dongle, etc.


Is it possible that:

  • The cable is port quality and should be replaced?
  • The Mac mini is having video output problems?
  • The monitor itself is faulty?


Before I commit to purchasing anything new I wanted to seek the help of some people much wiser than I. Thanks.


Alex


P.S. this has been happening pretty much ever since I got the Mac mini at release weekend back in 2018.

Mac mini, macOS 10.15

Posted on Jan 4, 2020 1:56 AM

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Posted on Jan 4, 2020 12:02 PM

FWIW, I had a similar issue with my 2018 Mac mini, running macOS Catalina, to my new Dell 4K monitor. I started by using a direct HDMI-to-HDMI connection using a HDMI 2.0 (Premium) cable. Like you, the issue occurs at either boot up or after a restart and only removing/reinserting the cable got it to work.


I then got the Belkin USB-C-to-HDMI adapter, along with the previous HDMI cable, which resolved the issue. Later I upgraded my mini to macOS Catalina 10.15.1. Being curious, I tried the direct HDMI cable connection again, and this time, it worked! ... and has continued to do so with the current 10.15.2 release.

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Question marked as Top-ranking reply

Jan 4, 2020 12:02 PM in response to AlexCossey95

FWIW, I had a similar issue with my 2018 Mac mini, running macOS Catalina, to my new Dell 4K monitor. I started by using a direct HDMI-to-HDMI connection using a HDMI 2.0 (Premium) cable. Like you, the issue occurs at either boot up or after a restart and only removing/reinserting the cable got it to work.


I then got the Belkin USB-C-to-HDMI adapter, along with the previous HDMI cable, which resolved the issue. Later I upgraded my mini to macOS Catalina 10.15.1. Being curious, I tried the direct HDMI cable connection again, and this time, it worked! ... and has continued to do so with the current 10.15.2 release.

Jan 4, 2020 7:54 AM in response to AlexCossey95

Look at your current HDMI cable. It should have a 1.2, 1,3, 1.4 or 2.0 version stamped on the connector ends.

see > https://denon.custhelp.com/app/answers/detail/a_id/192/~/differences-between-hdmi-versions


Bases on your description of the issues,

AlexCossey95 wrote:

If I swap out the cable for a HDMI to HDMI cable, it works, albeit at a lower quality/resolution (it's also dimmer for some reason).

After another few days, I get frustrated with the HDMI cable quality and swap back to Thunderbolt-DisplayPort and it works fine, but just for a few days, and then we start all over again. Any ideas what might be causing this?

I would first try getting and using a better quality 1.4 or 2.0 HDMI cable.

Jan 4, 2020 8:19 AM in response to den.thed

“It should have a 1.2, 1,3, 1.4 or 2.0 version stamped on the connector ends.”


If it does, it’s fake marketing. Genuine certified HDMI cables do not contain version numbers, instead they feature logos. See https://www.hdmi.org/resource/cables for the complete list.


Note that all of them should work although High Speed and Ultra High Speed are better, in that they indicate that the cables are test-certified for higher speeds.


Cables without logos or fake logos with numbers may and mostly also work. The official HDMI logo (only) indicates that the cable’s build quality meets or excess HDMI’s standards, which many manufacturers don’t bother with.

Mac mini connection to external display via USB-C/HDMI

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