iMac 2020 restarting randomly after connecting 2nd monitor

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iMac 2020 restarting randomly after connecting 2nd monitor

Hello, I just bought a new ASUS ProArt Display PA248QV to use as a second monitor for work. I have connected it to my iMac (Retina 5K, 27-inch, 2020) which is running MacOS Big Sur Version 11.2.3 and it seems to work for a random length of time, then the Mac goes black, the Asus monitor goes dark green and then everything reboots.

I then get a black error screen on the iMac saying that the "computer restarted because of a problem. Press a key or wait a few seconds to continue starting up." in various languages.

The monitor is connected through the HDMI cable that came in the monitor box, using a USB-C digital AV multi-port adaptor on the Mac end.

When the computer is working I am running an Excel doc, Teams, a couple of Chrome windows and Outlook only. There aren't many files saved to the Mac itself, but it looks like my 83,000 photos in iPhoto are taking up a load of room. I'm just working on freeing up an external hard drive to move the file location over to try to fix that, but I always seem to have iPhoto storage problems across my devices.

I've tried shutting the Mac down and restarting it myself; I've done all the suggested storage management suggestions under "About this Mac"; and the cables all seem to be connected properly. I'm just at a bit of a loss as the reviews on this monitor were great. Have I missed a glaring compatibility problem here? Any help would be gratefully received!! Thank you

iMac 27″, macOS 11.2

Posted on Apr 12, 2021 4:51 AM

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Answer 1

Apr 13, 2021 7:06 AM in response to P_Craft

Hello P_Craft,

It sounds like your video and mac function shuts down when using your external display for some time. We do have some links that include troubleshooting steps and isolation tips to help figure out what the issue might be. Have a look at them below:

Use external monitors with your Mac

Get help with video issues on external displays connected to your Mac

Something to consider, does the shutdown occur without the display connected after similar usage and time?

Thanks for posting in the Apple Support Communities forum.

Have a wonderful week!

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Answer 2

P_Craft Author

Level 1

11 points

Apr 21, 2021 4:22 AM in response to Nicholas_B2

Hi, thanks for your response.

It appears to be a random amount of time that I can use the iMac with the external ASUS monitor for. Then the external monitor goes green, the iMac screen goes black and I can’t do anything for approx 5 mins. Then it whirrs and restarts with an error message that it shut down unexpectedly.

I am connecting using official Apple USB-C Digital AV Multiport Adapter from the iMac with HDMI cable that came with the monitor.

I’m running Microsoft office, google chrome and teams - nothing too strenuous, and these crashes are very random. The be tried shutting down over lunch and restarting which sometimes works, but other times it will shut down after an hour.

it’s driving me mad and has cost me a days work so far. Is there any advice on an external monitor that will actually work? Thanks.

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Answer 3

ryane77

Community Specialist

Apr 21, 2021 5:36 AM in response to P_Craft

Hi P_Craft,

Thanks for the update. While there are additional third party options, there are too many to narrow down to one recommendation. Reviewing the Apple Store directly, here's a link to the External Monitor's offered by the company directly.

Hopefully this helps--take care!

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Answer 4

P_Craft Author

Level 1

11 points

Apr 21, 2021 6:27 AM in response to ryane77

Hmm for £4,599 for a monitor I might need to put up with the crashes :’) I’m more looking in the <£300 range

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iMac 2020 restarting randomly after connecting 2nd monitor

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