Dual monitors on mac mini 2018 do not turn ON reliable

I am running 2 x LG 4K 24UD58 from an unmodified mac mini 2018, 32GB, i7 via DP1.2 on TB3.

When it works (10% of all cases) it is perfect but the mac seems to have major problems turning these 2 displays ON. I have tried resetting, other DP/TB cables, detect-display-buttons and various scenarios.

Only when the displays are put to sleep and the mac mini is prevented from going to sleep then the screens turn ON reliable. If the computer is turned OFF or goes to sleep it does not turn ON both displays (90% of the time) and I need to reboot, turn displays ON/OFF and unplug/plugin monitors until both are detected by the mini and come ON. In 60% of all cases 1 of the 2 monitors come ON.

The monitors just indicate no signal received and go into power-safe.

Does anybody have a good advise I can try ? Thanks !

Mac mini, macOS 10.14

Posted on May 25, 2019 11:10 PM

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21,015 points

Posted on May 26, 2019 4:09 AM

Something else to try is a PRAM reset. In the boot phase it

forces the Mini to reload all available hardware and their configurations

if such information is reported by the devices. Make sure both displays

are active before doing this.

Reset NVRAM or PRAM on your Mac - Apple Support

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May 28, 2019 11:11 AM in response to Peter Hartman

Hi Peter,

Sorry for not responding sooner, we were traveling the last couple of days. Also sorry that staggering the TB3 ports did not totally fix the issue in this case.

I am glad, that you finally found a solution and then returned to share that experience with your fellow Apple users.

Another suggestion that I wanted to throw-up, was to just let the Mac Mini "Sleep" 24-7. Yep that's right, just let it sleep instead of shutting down. My Mac Mini's sleep for weeks or even months without any issues. Also because IMHO, sleeping 24-7 is actually easier on the hardware than repeated cold startups and restarts.

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May 27, 2019 12:48 PM in response to Peter Hartman

Also you should now try to Chang your mac’s power setting, like turner them off for chech and etc ..

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Dual monitors on mac mini 2018 do not turn ON reliable

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