Problems with DELL P2415Q monitor not waking from sleep.

I have two Dell P2415Q monitors hooked up to a MacPro (2013). I've followed the proper procedure to connecting them to the display port buses, etc.

The monitors work fine while they are on. Though I've noticed since upgrading to Yosemite that they do not properly awake after going into energy saver mode. My machine is setup to not go into sleep. Just put the displays to sleep after 10 mins.

At completely random times when I go to wake up the displays (hitting a keyboard key), one or both do not wake up. The Lights in the corner remain white and nothing appears. Even a restart doesn't seem to help, it's as if they are locked in a "deep sleep".

The only way to remedy the situation is to unplug the monitor power, and plug back in. Last night both got stuck, and I had to perform this fix on both individual – in other wards, neither reacted to the fact the other was "awakened".

I looked through the Dell settings and the energy saver settings are sparse at best.

Does anyone have any similar experiences with this or other displays recently?

Thanks!

Steve

Mac Pro, OS X Yosemite (10.10.2), 32GB RAM, 3.5Ghz 6-Core, Dual D500

Posted on Sep 22, 2015 7:05 AM

17 replies

Feb 3, 2017 1:10 PM in response to Stephen Barrante

Similar issues here. Monitor worked fine under Yosemite (I was slow to upgrade my Mac Mini) and never had this issue. After I went to Sierra in December, it started occurring. Now it's almost daily. I've tried every workaround posted except for replacing the cable (one's on the way) and no joy and I have to restart the Mac to fix.

This would seem to be a Mac issue as I've tried disconnecting the cable from the Mini and switching it to my MBP. The monitor immediately woke up and worked fine, but when I switched back to the Mini, it wouldn't respond. I suspect there's a driver issue that (pardon the layman's terms) the Mac think's it in one state and won't send another "wake up" signal to the monitor, or there are multiple levels of signaling and it's not sending the right one. Or possibly there's some HDCP protocol problem or key exchange that isn't taking place in certain scenarios.

Either way, the monitor clearly works, with that specific cable, and the only difference is which Mac it's hooked to.

neily9

Level 1

5 points

Mar 7, 2016 11:46 AM in response to Stephen Barrante

I had a similar problem.

But what worked for me was:

on the monitor, go to the "menu", choose "others" then on the "DDC/CI" option, change to "Disable" instead of enable

hope it works for u guys too

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Problems with DELL P2415Q monitor not waking from sleep.