Dell U2711 not waking properly after long sleep

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Dell U2711 not waking properly after long sleep

My 2014 Mac Mini works fine as does the Dell U2711 it is connected to via the display port.

However there is one issue - it doesn't happen all the time, but usually if left overnight or longer, and the Mac has gone to sleep, when I awaken it I know is is firing up (I can hear the disk spinning up etc.) and the display also comes to life (the orange light which means standby turns to blue which means awake) but the display remains blank. The only solution is to shutdown the mac and restart.

It only seems to happen after long period of sleep - if the mac has only been sleeping for, say, a couple of hours it is fine.

Any clues to what is going on. The only solution is not to allow it sleep the display which is not ideal.

With thanks.

Mac mini, OS X El Capitan (10.11.4), null

Posted on Apr 11, 2016 1:32 AM

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Answer 1

sterling r

Community Specialist

Apr 12, 2016 9:26 AM in response to adetri

Howdy there Aderti,

It sounds like your external monitor isn't engaging properly when you wake it from sleep. I was looking through our support articles and I would suggest using the troubleshooting in this one about issues with a computers sleep and wake process:

If your Mac doesn‘t sleep or wake when expected

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.

Thank you for using Apple Support Communities.

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