uxjade
Level 1 (8 points)
Desktops

Q: iMac will not wake from sleep when external monitors are plugged in

I bought my imac to use it with a second monitor and my TV. I have them both plugged in through thunderbolt converters (HDMI for TV and VGA for montior). If I leave them plugged in and my mac goes to sleep, the mac display will not wake up again. I have to hold the power button to shut down and restart before my imac will work again. I've tried both external displays on their own and they both cause the same problem.

 

This also only happens when I leave my computer to sleep overnight. If it goes to sleep for a few seconds and I wake it up, there are no issues with the displays.

 

I'm sick of having to unplug and replug every time I want to let my computer go to sleep. Any idea on how to fix this?

iMac, OS X El Capitan (10.11.5)

Posted on Jul 22, 2016 5:02 PM

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uxjade

Q: iMac will not wake from sleep when external monitors are plugged in

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  • by Alwayswantingtohelp1,

    Alwayswantingtohelp1 Alwayswantingtohelp1 Jul 23, 2016 3:06 PM in response to uxjade
    Community Specialists
    Jul 23, 2016 3:06 PM in response to uxjade

    Hello uxjade,


    Thank you for using Apple Support Communities. 


    From your post, I understand that your Mac does not wake up when you leave your external displays plugged in for extended periods of time. I understand not wanting to restart your Mac every time you want to wake it up. I recommend using the steps in the sections called "If your Mac doesn't wake when you expect" and "If the previous steps don't work" from the following article: 

     

    If your Mac doesn‘t sleep or wake when expected

     

    If your Mac doesn't wake when you expect

    Your Mac might pause a few seconds before it wakes up. If it doesn't seem to wake at all, check for these possibilities:

    • Your screen brightness might be turned down.
    • If you're using an external display, your display might be turned off. 
    • Your Mac might be in safe sleep. To wake from safe sleep, press the power button.
    • Check for a sleep indicator light, if applicable, and make sure that your Mac isn't turned off.

    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. 

     

    Cheers