Display won't come on and external drives won't show with Mac Pro

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Level 1

105 points

Display won't come on and external drives won't show with Mac Pro

One of my displays isn't coming on. I'm supposed to have two. Also, the mouse and keyboard wouldn't come on, until I restarted. I am using a KVM. Then Xcode wouldn't run a project. Then one of my external drives doesn't show in Finder. Then the other external drive would disappear from Finder and then reappear.

Is there something going out in my hardware. It's a new Mac Pro. I'm using the macOS Monterey version 12.0.1.

[Re-Titled by Moderator]

Mac Pro, macOS 12.0

Posted on Dec 15, 2021 10:41 AM

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Answer 1

Best reply

Grant Bennet-Alder

Level 10

127,483 points

Dec 15, 2021 10:58 AM in response to madirmur59

RE: displays:

to get a Mac display to become active, you need the Mac to query the display, and the display to answer with its name and capabilities. Otherwise, the display will not be shown as present, and no data will be sent to the display. "No signal detected" is generated by the DISPLAY, not by the Mac.

This query is only sent at certain times:

• at startup

• at wake from sleep — so momentarily sleeping and waking your Mac may work

• at insertion of the Mac-end of the display-cable, provided everything on that cable is ready-to-go

• on invoking Option-(Detect Display) button in Displays preferences (from another display)

so try doing some of those things and see if the display comes alive.

If you use a KVM, you may cut off the display from the Mac, and then it can not answer, so it will stay dark.

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Answer 2

madirmur59 Author

Level 1

105 points

Dec 15, 2021 1:20 PM in response to Grant Bennet-Alder

"• on invoking Option-(Detect Display) button in Displays preferences (from another display)"

By "Option", do you mean the Option key on the keyboard?

I am not able to find "Detect Display" button in Display preferences.

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Answer 3

madirmur59 Author

Level 1

105 points

Dec 15, 2021 5:34 PM in response to Grant Bennet-Alder

What I was saying in my last comment was that when I hold the Option button, the Detect Displays button doesn't appear like it's supposed to. The Help section that comes with the macOS says in the Help section for Display preferences that the Night shift button would change into the Detect Displays button when I hold down the Option button.

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