ericnepean
Level 1 (73 points)
Mac OS X

Q: Mini Display Port bug causing sleep issues in 10.11.5

I received a refurb  27" iMac (iMac 17,1) a few weeks ago. I immediately updated to 10.11.4, and last week to 10.11.5. Upon the upgrade to 10.11.5 it acquired some new unwanted behaviour -  when I found it in sleep, I quite often was unable to wake it, and had to reboot.

 

At first I thought it was a problem with deep sleep, but then I noticed the problem also occurs in normal sleep.

 

After much debugging this weekend I have narrowed the problem down to the following: If a mini display port adapter (to DVI or VGA) is connected to any of the thunderbolt ports, after some period of time greater than 45 minutes but less than 75 minutes, the iMac is unable to wake from sleep, and requires a reboot.

 

This behaviour is the same if I connect the mini display port adapter to the thunderbolt connector on the iMac or on my Thunderbolt dock.

 

I've tested two mini display port to DVI adapters, and one mini display port to VGA adapter, with the same result. (I don't have any other mini display port adapters) My testing is with a NEC P232W monitor. I've previously used these adapters on other systems with no problem.

 

(If I could downgrade this machine to 10.10, I would. I have the installer, but I don't think it will support this version of hardware)

iMac (Retina 5K, 27-inch, Late 2015), OS X El Capitan (10.11.5), i7, 16GB, 1TB Fusion

Posted on May 23, 2016 6:31 PM

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ericnepean

Q: Mini Display Port bug causing sleep issues in 10.11.5

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  • by norm123,

    norm123 norm123 May 25, 2016 6:29 AM in response to ericnepean
    Community Specialists
    May 25, 2016 6:29 AM in response to ericnepean

    Hey ericnepean, 

    I understand that you are having issues with your iMac waking from sleep with the display adapters plugged in. You have had success with those previously and the issue is the same across 3 adapters. Let's see if we can get it sorted out. 

    Based of the extended troubleshooting that you have done so far, you might have already tried one or more of the follow steps below. 

    If your Mac doesn‘t sleep or wake when expected
    https://support.apple.com/en-us/HT204760
     

    If the previous steps don't work

    These additional steps may help identify or resolve the issue: 

    • Reset the SMC.
    • Reset NVRAM.
    • Disconnect external devices other than your Apple keyboard, mouse, and display. If that resolves the issue, gradually reconnect your devices, testing each time, until you find the device that is interfering with sleep. Then check the documentation that came with the device, or contact the device manufacturer.
    • Start up in Safe Mode to see if the issue is related to non-Apple startup items, login items, or kernel extensions. 
    • Try to isolate the issue by using another user account. 


    I would try the SMC and NVRAM resets alongs with trying to reproduce the issue in Safe Mode.  If that does not work, let me know and I will suggest some other things to try. 

    Take it easy


     

  • by ericnepean,

    ericnepean ericnepean May 25, 2016 9:21 AM in response to norm123
    Level 1 (73 points)
    Mac OS X
    May 25, 2016 9:21 AM in response to norm123

    Hi Norm, thanks for the comments.

    My first call with Applecare identified the SMC rest, PRAM rest and safe boot procedure, I've executed that, and re-executed again during trouble shooting.

    I first disconnected all peripherals and observed the problem disappear.

    I reconnected all but Thunderbolt - everything OK.

    I reconnected all Thunderbolt- problem appears.

    I discovered by observing logs that the problem occurs before deep sleep

             - it occurs between 45 minutes and 75 minutes after initiating sleep

             - it occurs at the end of the first dark wake cycle during sleep

             - pmr error code is sometimes -40

    I juggled combinations of thunderbolt connections to find

      - not dependent on presence or absence of CalDigit thunderbolt dock

      - not dependent on Thunderbolt to firewire adapter

      - not dependent on Thunderbolt ESATA connection to drive dock

      -occurs if miniDisplay to DVI is present on iMac or thunderbolt dock

      -occurs if miniDisplay to VGA is present on iMac or thunderbolt dock

      - occurs if HDMI to DVI is present on thunderbolt dock

    I then turned to energy saver settings (with mini display to DVI connected to iMac)

    I set Energy Saver settings to Default (they were non Default) - problem remains

    I disabled all energy saver settings - problem gone

    There are 4 settings - it's one or both of the top two.

     

    Second call with Applecare, the rep suggested that I test with a different display (this display is NEC P232W)

    If problem does not occur with other display, then NEC P232W is no longer compatible with OSX.  (what !!?!??!! )

    If problem does occur with other display, bring it in to the Apple Store for further checking

     

    His guess - this is a refurbished iMac, possible issue with the Thunderbolt board inside the iMac

     

    It would very handy if there was a way of immediately triggering the dark/wake cycle, instead of having to wait an indeterminate time.