Mattzda3
Level 1 (5 points)
iPhone

Q: Multiple Displays have problems with El Capitan

I upgraded to El Capitan last week. Immediately after restarting from the install, my 2nd and 3rd monitors no longer displayed anything. It's like they were turned off. I tried restarting, but nothing changed. I then tried switching cables to different ports and seeing what would happen with just a single monitor plugged in, here's what I found.

 

Machine Info:

MacPro

32GB RAM

AMD FirePro D500 3072 MB Graphics

 

27" Apple Cinema Display (x2) using Thunderbolt

13HD Wacom Cintiq using HDMI

 

-------------------------

When 1 monitor was plugged in, it would work fine.

When 2 were plugged in, only the first monitor would work

It seems that changing ports made no difference, only 1 monitor would work at any given time. I also had issues with some external drives failing to mount.

 

I called AppleCare and they had me reset the SMC on the MacPro. This seemed to fix it until I setup my second cinema display with Apple Calendar and Apple Mail in the new split view and quit the applications without exiting SplitView first. Doing this blacked out the second Cinema display and I had to repeat the SMC reset procedure (listed below). It happened again about an hour later after a restart, I called AppleCare again and the tech led me through the SMC reset steps again and all monitors began working properly again. Within the next few hours the same problem happened again...I am now back on Yosemite until I see something indicating this problem is fixed.

 

I noticed that Beta users had this problem documented quite a bit on the .3 release, but I saw that the .4 release seemed to fix the issue. Well, it did not. I caught lightening in a bottle and it's happening to me.

 

 

 

SMC Reset Procedure

1. Shut Down computer if it's not already shut down

2. Unplug all peripherals and computer for 30 seconds

3. Plug in computer to power and one monitor

4. Start-up and check to see if monitor is working

5. If monitor is working then plug-in second display and restart

 

This worked for me and I was able to plug up the other peripherals.

 

I'm not sure why the problem persists, but everything is completely stable and operates fine on Yosemite.

Mac Pro, OS X Yosemite (10.10.5), iMac 27" 8GB i7

Posted on Oct 5, 2015 9:36 AM

by Luis Sequeira1,Apple recommended
Luis Sequeira1 Luis Sequeira1
Level 6 (11,919 points)
A:

Rdruhl wrote:

 

That is interesting that you have to use the Option key. Why did they not just make another button? And how did you know that you had to use the Option key? Anyway, I tried it, and I still do not get the Menu or Dock on the second display.

 

Try System Preferences->Mission Control

It appears that the setting for "Displays have separate Spaces" was lost. You need to have that box CHECKED in order to have menu bars (and the dock, if it is set to appear at the bottom) on every display.

You need to log out and log back in for this change to take effect.

Posted on Oct 12, 2015 8:48 AM

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Mattzda3

Q: Multiple Displays have problems with El Capitan

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  • by sorenmadsen,

    sorenmadsen sorenmadsen Oct 6, 2015 12:07 AM in response to Mattzda3
    Level 1 (0 points)
    Oct 6, 2015 12:07 AM in response to Mattzda3

    I have a similar issue. I have a Macbook Pro Retina and two external Dell monitors.

     

    Everything worked fine before I unplugged my two external monitors yesterday to leave work and plugged them in again this morning.

     

    At first, monitor two didn't come/turn on, so I tried switching ports – and now none of my two external Dell monitors will come/turn on.

     

    I had the Macbook set up with a Mail/calendar split view – and monitor three setup with two Terminal windows split view.

     

    I will try the SMC reset procedure – but this is obviously not a sustainable solution, for someone who plugs/unplugs several times a day to go to meetings etc.

     

    MacBook Pro (Retina, 15-inch, Early 2013)

  • by BasementJack,Helpful

    BasementJack BasementJack Oct 7, 2015 9:57 AM in response to sorenmadsen
    Level 1 (32 points)
    Oct 7, 2015 9:57 AM in response to sorenmadsen

    Does "Detect Displays" help in this case?

     

    You get that by opening the displays preference, and holding down the option key:

    2015-10-07_11-55-30.png

  • by Rdruhl,

    Rdruhl Rdruhl Oct 7, 2015 10:33 AM in response to Mattzda3
    Level 1 (0 points)
    Oct 7, 2015 10:33 AM in response to Mattzda3

    In my case, the Menu Bar and the Dock no longer show on my second display.

  • by sorenmadsen,

    sorenmadsen sorenmadsen Oct 7, 2015 11:38 PM in response to BasementJack
    Level 1 (0 points)
    Oct 7, 2015 11:38 PM in response to BasementJack

    Ahh – never caught that, that "Detect Displays" is now hidden that way.

    In this mornings variant of the issue, "Detect Displays" actually helped – so thank you very much!

  • by Rdruhl,

    Rdruhl Rdruhl Oct 8, 2015 9:42 AM in response to Mattzda3
    Level 1 (0 points)
    Oct 8, 2015 9:42 AM in response to Mattzda3

    I went through the SMC Reset Procedure, and it did not help. I still have no Menu and no Dock on the second display.

  • by Rdruhl,

    Rdruhl Rdruhl Oct 8, 2015 9:45 AM in response to BasementJack
    Level 1 (0 points)
    Oct 8, 2015 9:45 AM in response to BasementJack

    That is interesting that you have to use the Option key. Why did they not just make another button? And how did you know that you had to use the Option key? Anyway, I tried it, and I still do not get the Menu or Dock on the second display.

  • by apleased,

    apleased apleased Oct 8, 2015 11:22 AM in response to Rdruhl
    Level 1 (0 points)
    Oct 8, 2015 11:22 AM in response to Rdruhl

    Same issue on MacBookPro with an upgrade to El Capitan. Things worked fine initially with two external monitors at work. Went home and plugged in two different monitors. That worked fine. Issues appeared after returning to work and plugging in the original two monitors:

    1. the dock and menu only one one monitor

    2. graphics issues (slow performance, application windows flickering)

     

    From this point onwards the system only works ok without external monitors, or with only one external monitor but only with mirroring.

  • by JimmyCMPIT,

    JimmyCMPIT JimmyCMPIT Oct 8, 2015 11:43 AM in response to apleased
    Level 5 (7,060 points)
    Mac OS X
    Oct 8, 2015 11:43 AM in response to apleased

    there are a handful of posts on this forum and others where dual monitor mac users are having some form of an issue with their setups. Some owners of older Mac Pro's have said they're rebooting sporadically. I have not tested it out at this time so that's all the info I found at this time.

  • by Mattzda3,

    Mattzda3 Mattzda3 Oct 12, 2015 8:36 AM in response to BasementJack
    Level 1 (5 points)
    iPhone
    Oct 12, 2015 8:36 AM in response to BasementJack

    The "detect displays" button did not help. It's like neither monitor actually powers up after El Capitan was installed. I can plug each of them up individually and they work fine, but they don't all work together.

     

    I didn't find other threads with this specific problem in it, so if someone sees another thread with a solution please link to it here. I would really appreciate it.

  • by Luis Sequeira1,Apple recommended

    Luis Sequeira1 Luis Sequeira1 Oct 12, 2015 8:48 AM in response to Rdruhl
    Level 6 (11,919 points)
    Oct 12, 2015 8:48 AM in response to Rdruhl

    Rdruhl wrote:

     

    That is interesting that you have to use the Option key. Why did they not just make another button? And how did you know that you had to use the Option key? Anyway, I tried it, and I still do not get the Menu or Dock on the second display.

     

    Try System Preferences->Mission Control

    It appears that the setting for "Displays have separate Spaces" was lost. You need to have that box CHECKED in order to have menu bars (and the dock, if it is set to appear at the bottom) on every display.

    You need to log out and log back in for this change to take effect.

  • by Rdruhl,

    Rdruhl Rdruhl Oct 12, 2015 9:04 AM in response to Luis Sequeira1
    Level 1 (0 points)
    Oct 12, 2015 9:04 AM in response to Luis Sequeira1

    Thanks, Luis, that did the trick! I am a happy man again!

  • by Luis Sequeira1,

    Luis Sequeira1 Luis Sequeira1 Oct 12, 2015 9:06 AM in response to Mattzda3
    Level 6 (11,919 points)
    Oct 12, 2015 9:06 AM in response to Mattzda3

    I don't know what is causing this. I guess I am lucky - or you are unlucky.

    Since installing El Capitan I have used my rMBP with different external displays, either connected through HDMI or Thunderbolt, with or without adapters, with zero issues. I have used it in my office at work, in my home office, in the living room, in my bedroom, in lectures connected to projectors. In some of those I used it while mirroring the display, in others as extended desktop. The OS remembers this, as well the relative positions of the displays.

    I had not, however, used two external displays at the same time. So I loaned my colleague's monitor, and attached it, as well a 21.5" iMac.

    All three displays worked fine together, and I can rearrange their locations at will.

  • by Mattzda3,

    Mattzda3 Mattzda3 Oct 12, 2015 10:41 AM in response to Luis Sequeira1
    Level 1 (5 points)
    iPhone
    Oct 12, 2015 10:41 AM in response to Luis Sequeira1

    I will keep this in mind when I jump back up to El Capitan. I am now back on Yosemite and waiting for Wacom Cintiq drivers. Thank you for the responses.

  • by millport,Helpful

    millport millport Oct 17, 2015 2:44 PM in response to Mattzda3
    Level 1 (5 points)
    Oct 17, 2015 2:44 PM in response to Mattzda3

    I have an iMac with a second larger LED Cinema display. The menu bar is at the top of the larger display and I use that as the primary screen. When I power up with El Capitan both displays come up as normal but within a short time the 2nd display goes blank. I am now on 10.11.1 Beta (15B38b) and the problem persists. I have reported it through the Apple Feedback Assistant.

     

    Oddly, if I take a screen shot of both displays (Shift+Command+3) the screenshot of the blank display is captured normally. That is, the OS thinks it is displaying the screen even when the physical display is blank.

     

    I have found a workaround for now.

     

    Power off iMac.

    Cut power to 2nd display

    Disconnect mini display port and USB connectors from back of iMac

    Power up iMac and let it start up as a single-display system

    When everything has loaded, plug external display into back of iMac

    Apply power to 2nd display.

     

    The system will then reconfigure itself with two displays and behave normally from then on. You just can't boot the whole system up with the second display connected.

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