external 4k monitor not waking up from sleep mode

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external 4k monitor not waking up from sleep mode

Hello everyone,

Sorry if this is a repeat, but I could not find a similar issue anywhere else.

I am having a problem with an external ASUS PB287Q 4k monitor connected via displayport 1.2 to my Retina iMac.

It works fine until the mac goes to sleep (automatically due to idle timeout, or manually) and does not detect a signal when the Mac wakes up.

Forcing it to check (by pressing power briefly) makes the monitor scan and it still says no signal. I have to turn it completely off and on for a signal to be detected.

I suspect this is a problem with the iMac and not with Monitor, because this monitor works just fine with my late 2013 Retina Macbook pro.

iMac with Retina 5K display, OS X Yosemite (10.10.1), Asus pb287Q displayport 1.2

Posted on Dec 22, 2014 7:47 AM

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Answer 1

brenden dv

Community Specialist

Dec 23, 2014 9:16 AM in response to sramabadran

Hi sramabadran,

I'm sorry to hear you are having issues with the video out via DisplayPort on your iMac. If you continue to have detection issues after your Mac wakes from sleep, you may find the troubleshooting steps outlined in the following article helpful:

Apple computers: Troubleshooting issues with video on internal or external displays - Apple Support

You may also want to try testing it by setting only the displays (not the machine) to sleep, and see if the issue persists:

OS X: Saving energy with Sleep - Apple Support

Regards,

- Brenden

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Answer 2

sramabadran Author

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Dec 24, 2014 3:58 AM in response to brenden dv

Hi Brendan,

I have gone thru the steps in the troubleshooting guide.

As described above, the monitor works perfectly with my late 2013 Macbook Pro (Retina) 15".

When the display is put to sleep, and the Asus monitor goes into Standby mode, the iMac is not sending any signal to the device when the display is rewoken. Making the display re-scan for a signal is not sufficient. I have to turn the display off and on, for the iMac to detect it again.

I tried calling Apple and have opened a ticket as well, the the support line keeps hanging up on me when they hear the problem. I guess its too complicated for them to deal with during this holiday season, and they would rather deal with a simple return. ;-P

Not sure what next steps to follow. Has no one else opened a similar ticket. I have found other reports of this problem on various forums.

Shiva

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Answer 3

Feb 17, 2015 1:16 AM in response to sramabadran

I do have the same problem, and I still without a solution!

Is very annoying, be necessary to turn off and on the screen each time that I look the screen....

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Answer 4

May 12, 2015 9:20 AM in response to sramabadran

I have the same problem. It's very sporadic and happens unpredictably. The simplest solution for me is to unplug the second monitor and immediately plug it back in. Kind of a pain. I used to have the same problem on another iMac running snow leopard. Using the Display preference, I could tell the computer to identify the monitors (i.e., 1 & 2 show up on each display respectively) and the second monitor would wake up again. Mavericks seems to have lost this feature.

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Answer 5

Oct 6, 2015 9:06 AM in response to sramabadran

I also have this problem. I have a brand new 2013 Mac Pro that I bought to replace my old Mac Pro 3,1. I'm using the same ASUS 27" 4K monitor, and used it with both machines. On the old MP 3,1, it worked without issue. On the new 2013 MP the screen does not turn on after Energy Saver has turned off the display. This problem doesn't happen when I use an HDMI cable, but as that is limited to 4K at 30htz, it's not desirable, I want the 4K at 60htz that DisplayPort 1.2 provides.

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