Two Thunderbolt 3 ports on iMac Pro suddenly stopped working. Other two work fine.

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Two Thunderbolt 3 ports on iMac Pro suddenly stopped working. Other two work fine.

I'm numbering the ports from right to left, facing the back of the computer.

UAD audio interface plugged into 1st port. LaCie 2big dock plugged into 2nd port. 4K monitor plugged into 3rd port via HDMI to Thunderbolt 3 adapter. Suddenly the light goes off on the LaCie drive and the audio interface is no longer recognized. The monitor still works fine.

I unplugged everything and restarted the computer. The monitor wouldn't work in the first two ports either. The audio interface and LaCie drive work fine connected to 3rd and 4th port.

Posted on May 29, 2019 10:32 AM

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Answer 1

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Joseph_S.

Community Specialist

May 30, 2019 7:12 AM in response to zephan

Hi zephan,

Thank you for posting in the Apple Support Communities. I understand you're finding that two of your Thunderbolt 3 ports aren't recognizing devices.

It sounds like you've done some great isolation by interchanging your ports and devices. Have you tried a reset of the System Management Controller on your iMac Pro? How to reset the System Management Controller (SMC) on your Mac

"How to reset the SMC on a Mac that has the Apple T2 Security Chip

Follow these instructions for Mac computers that have the Apple T2 Security Chip.

Mac desktop computers with the T2 chip

Try this first:

Choose Apple menu > Shut Down.
After your Mac shuts down, press and hold its power button for 10 seconds.
Release the power button, then wait a few seconds.
Press the power button again to turn on your Mac.

If that doesn't resolve the issue, follow these steps:

Choose Apple menu > Shut Down.
After your Mac shuts down, unplug the power cord.
Wait 15 seconds.
Plug the power cord back in.
Wait 5 seconds, then press the power button again to turn on your Mac."

If the issue persists, try testing in a temporary administrator account on your Mac: How to test an issue in another user account on your Mac. Knowing whether you can replicate the issue there would help to determine more about the root cause.

Cheers!

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