iMac 5K (2016) won't wake at all with external monitor plugged in

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iMac 5K (2016) won't wake at all with external monitor plugged in

I have a brand new 27" 5K iMac. My first Mac from Windows - it's been a world of frustration and while most things I've re-learnt or found work-arounds for, I have a major issue of the iMac not waking up from sleep. It took days of changing things and narrowing it down to discover it was an external monitor causing the issue.

I have an LG 23MP75 IPS monitor plugged in at 90 degrees. It's a debug, bash and chat screen. So I develop sites on the main iMac screen in Sublime editor and also view the sites in the browser on it, then on the external I have chrome inspector, terminal and Skype/chat stuff. When the machine is on, it works well, no issues. If it goes to sleep for a short period of time like 30 mins or less, it wakes. If it goes into a deep sleep (hibernation?) then it will not wake. Sometimes holding down cmd+ctrl+p+r and powering on works but mostly not, typically I have to pull out the power cord ! for a reboot. Heartbreaking. The only solution right now it to unplug the HDMI before I go home every day.

The external monitor is connected via HDMI cable which goes into an 'active' HDMI to Mini-display port adaptor. I was told that the adaptor being active is important after I had a non-active one and bought an active one to try to resolve this. I read deleting the hibernation file might help to allow OSX to replace it but I opened it instead and it's blank so not corrupt (sudo rm /var/vm/sleepimage).

If I shutdown and restart, the login screen is badly laid out, it's mirrored display not extended display which is how it's set-up. See images to compare. This makes me wonder if part of the problem is OSX being unhappy with the monitor config outside of being logged-in?

Here's the monitor set up config so you can see it's nothing out of the ordinary:

There's no odd set-up, the machine was brand new from Apple themselves, default out the box, no restore or anything like that as I'm new to Mac.

Can anyone offer any suggestions to fixing the issue so I don't have to either unplug the cable or shut-down (which leads me to see the horrible mirrored login every morning)? Any help would be greatly appreciated.

iMac with Retina 5K display, iOS 9.3.3

Posted on Jul 28, 2016 6:32 AM

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Answer 1

Jan 30, 2017 5:43 AM in response to tobzzzz

I've had this exact same problem. The core problems seems to be related to going into hibernation, i.e. deep sleep that stops disk access. I have a 27" Dell display connected using the miniDP connector.

Here's what worked for me (YMMV): Go to System > Prefs > Energy Saver

Make sure that "Prevent computer from sleeping automatically when the display is off" is checked.

Make sure that "Put hard disks to sleep when possible" is unchecked

Other posts I've read also talk about active vs. inactive display port connectors. I believe having an "active" connector might yield better results, but since the above Energy Saver settings worked, I've not pursued it further.

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Answer 2

rkaufmann87

Level 10

148,452 points

Jul 28, 2016 7:46 AM in response to tobzzzz

You have 90 days of free AppleCare telephone support, have you called Apple to discuss and see what solution they may have? If you were not aware you had the 90 days of AppleCare support please click http://www.apple.com/support/complimentary/. Also, if you have not already, I would strongly recommend buying AppleCare, this will extend the warranty to 3 years and provide 3 years of phone support. If your machine ever needs a repair (lets hope it never does) AppleCare pays for itself almost always on the first incident.

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