Mac Pro cylinder has problem with second monitor

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Level 2

185 points

Mac Pro cylinder has problem with second monitor

I have a Mac Pro cylinder (late 2013) that has had both a thunderbolt and cinema display attached. For a while, it was fine. Then the cinema display seemed to die, so I connected another cinema display -- then, that eventually died. Interestingly, the display I thought that died worked fine on another system.

So we decided to just put another thunderbolt display on. Powered up fine. I come in the next day and the second monitor is off.

Sometimes, unplugging it in/out will solve the problem, and I recall this worked "for a while" with the older displays.

This leads me to believe there is an underlying problem, possibly with the thunderbolt connections in the cylinder itself, and it's become a big annoyance.

Has anyone more information about what the problem might be?

Yes, I have recently reset the *RAM, which I understand happens when you power it down and unplug it for a time.

The OS is up to date, 15.3.0 Darwin Kernel, El Capitain 10.11.3.

Thank you.

Mac Pro, OS X El Capitan (10.11.2)

Posted on Mar 3, 2016 10:41 AM

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Answer 1

Mar 3, 2016 10:52 AM in response to Forrest

Make sure you do not have both displays on the same ThunderBolt Bus:

Use multiple displays with your Mac Pro (Late 2013) - Apple Support

Beyond that, there do seem to be "ghosts" in the system that lights up the second and subsequent displays after various system events such as wake-from-sleep.

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Answer 2

DonH49

Level 6

16,710 points

Mar 3, 2016 10:54 AM in response to Forrest

Try this and report back.

Connect the Apple thunderbolt display to bus 0 port 6. Connect the other Apple thunderbolt Display to bus 2 port 4. Then look at ASP under thunderbolt and both should be at the top of the thunderbolt chain relative to its bus. The route string should read 1.

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Answer 3

Forrest Author

Level 2

185 points

Mar 3, 2016 11:39 AM in response to DonH49

This re-arranged how my displays are presented, so my primary is up on my stacked books (where my second monitor is). The system thinks that the second display is now my primary monitor -- the System Settings to arrange the displays doesn't work.

I can't just move them as I have cable management here... who writes this stuff? LOL

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Answer 4

Mar 3, 2016 11:48 AM in response to Forrest

The arrange window is supposed to assign "primary" to the display onto which you drag the tiny menuBar:

.

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Answer 5

Forrest Author

Level 2

185 points

Mar 3, 2016 12:39 PM in response to Grant Bennet-Alder

Thank you, I didn't realize that. It's actually not very obvious (UI improvement there).

Now, I'm having some really funky USB issues with the keyboard. I had to plug the keyboard into the new (second) monitor for it to work! It wouldn't work in any port of the Mac itself or the (switched) primary display.

In fact, as I seem to recall, some of the issues I had with the old monitors seemed to coincide with connecting other USB devices (ie: a USB disk or disc). This feels like there is a firmware bug somewhere. ?

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Answer 6

Mar 3, 2016 1:12 PM in response to Forrest

keyboard-on-a-USB-Hub (including the USB Hub in a display) works for everything EXCEPT the 'snag keys' you need occasionally at Startup. When on a Hub, the hub come up too late to send the key codes in time, and the 'snag-keys' get missed.

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Answer 7

Forrest Author

Level 2

185 points

Mar 3, 2016 1:18 PM in response to Grant Bennet-Alder

It does get stuck on boot, but I had the keyboard plugged in directly to the Mac Pro. I tried different slots, too -- didn't work until I plugged it in to my *second* display. That seems really messed up.

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