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Giacecco Author

Level 1

20 points

El Capitan unstable when connecting to external monitor using DisplayPort

I have a MacBook Pro Retina 15" mid-2015, 2.8 Ghz Intel Core i7, 16Gb RAM running MacOS 10.11. The external monitor is an Asus MX299Q.

Before El Capitan I did not have this issue.

When I connect the external monitor via Display Port - that is my preference - the photos below show what I see. The photos are from three different attempts. Apparently the same does not happen using HDMI. The issue happens:

- when I turn off the external monitor and turn it on again, and

- when I connect the external monitor after using the laptop's own display

I would like to quickly understand if it is a hardware or a software problem, so that at least I know where to go next. The way the issue started with El Capitan suggests the latter. Thanks.

Giacecco

If I detach the external monitor and try to use the laptop's display, two times the display was ok but the system was unstable and I could slowly manage to close all applications and restart. Once, though, the problem was still there, as you see here, and I had to force turn-off and on again:

MacBook Pro with Retina display, OS X El Capitan (10.11), 15-inch, mid-2015, 16Gb RAM

Posted on Oct 4, 2015 12:09 AM

Top-ranking reply

sterling r

Community Specialist

Posted on Oct 13, 2015 12:19 AM

Hello there Giacecco,

It looks like you're seeing some unexpected graphical anomalies between your internal and external displays. I would suggest the troubleshooting in the following article to help you troubleshoot this issue:

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

This section in particular:

If more than one video adapter is in use (or "daisy-chained"), troubleshoot by using only one adapter.
Example: A mini DisplayPort to DVI adapter connected to a DVI to HDMI adapter is an unsupported configuration because there is a series of adapters in use.

If available, try using a different display and or adapter (or use a different connector by using DVI instead of VGA, for instance).

Reset the system

You can reset the Mac's parameter RAM and SMC.

Reset the resolution

Start up in Safe Mode.

From the Apple () menu, choose System Preferences.

Choose Displays from the View menu to open the preferences pane.

Select any resolution and refresh rate that your display supports.

Restart your computer.

Thank you for using Apple Support Communities.

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66 replies

Jul 25, 2016 1:54 PM in response to Eric Root

Thanks... I thought that is what I was doing... 😁

Jul 28, 2016 2:34 PM in response to Giacecco

I may have found a solution. On a whim I purchased this - https://www.amazon.com/Mini-DisplayPort-HDMI-Active-Adapter/dp/B01B702YTG?ie=UTF 8&m=A590JFSRVCU25

Now, my display has a HDMI 2.0 input (that supports 4k) so I thought that maybe, it's simply a display port issue. So, from my Macbook Pro, I connected the above adapter (into Thunderbolt) connected an HDMI cable (capable of 4K) from the adapter to the display.

No wake crashes. Still slow wakes, but I assume that's the display's fault because I can use the keyboard to login after wake before I see anything on the display.

Crossing my fingers.

I've let it sleep over night (hard disk shut down sleep) - I've turned my display off and on, running with screen savers.... so far so good. I've had this going for about 4 days now.

Ill keep you all posted.

Sep 7, 2016 8:30 PM in response to suchastrangenumb

Did buying the Active Adapter work?

As of September 7, 2016, this is still happening to me with my 15" Macbook Pro and a Dell 4k 27" monitor. When connected via Display Port, it has all sorts of sleep/wake crashes, where the external display and the laptop display go black and I have to do a hard restart.

Sep 8, 2016 7:29 PM in response to Giacecco

Hi there, (September 8th, 2016)

Tonight, I updated from Mavericks (10.9) to 10.11.6 because a software I bought needed to run on El Capitan.

I have a MBP Retina 13inch late 2013 with Intel Iris 1536Mo.

My macbook is plugged into my HDTV through the HDMI port of my MBP. I also use a self-powered USB hub for a USB mouse, keyboard and external soundcard. Never had any problems so far. In my second USB port, I have an external hard drive plugged in through USB3.

After the update, I logged in to my user as I normally do. After less than a minute of opening the finder and google Chrome, my screen froze completely. Couldn't move the mouse or do anything. I had to perform a hard reset. After another boot, same thing happened, sometimes after a minute, sometimes after 30 seconds. I tried not opening Chrome to see if it had something to do with it, but no. Sometimes, my MBP would auto reboot after freezing.

The freezing did not happen in Safe mode, but when opening a browser, everything was going really weird, with some flashes and graphic glitches. Could still use it though.

After reading this thread, I tried shutting down my computer, unplugging everything, and boot up without any external stuff plugged in. Bam! No more crashes.

I understand that some people changed the cable or adaptors they were using to fix this issue, but it makes no sense to me as it was working perfectly 2 hours ago on my old OSX version.

I will now one by one plug back my USBs and HDMI in and see if the freeze comes back. To be continued.

Sep 8, 2016 7:48 PM in response to marcremillard

Well, for now at least, it seems like the freezing problem is not coming back. Maybe I just had to unplug my HDMI and plug it back in to fix the issue. Will post if it ever happen again.

What I did :

1. Boot computer
2. browse the internet and see if anything happens

3. plugged my usb HUB in

4. plugged my external hard drive in

5. plugged my HDMI cable in.

No crashes. maybe I was just lucky.

rdapple

Level 1

4 points

Nov 22, 2016 3:58 PM in response to Giacecco

Macbook Pro 15 Retina + Dell P2415Q 4K monitor connected by DisplayPort 1.1 cable.

On wake from display sleep (MBP never sleeps), my Dell P2415Q is mirrored (normally not) at a login screen as the Macbook Pro has rebooted from a crash.

Just switched to test an Accell DisplayPort 1.2 cable (recommended by VESA DisplayPort working group) which fixed boot-up problems on a PC connected to same Dell 4k monitor. (On boot, with a bad DP 1.1 cable, PC would immediately shut off and try to boot up again, in an endless 1 second cycle, due to the powered 20th wire feeding power back into video card causing this weird issue.)

Apparently cheap brands of DisplayPort cables don't follow the DP 1.2 specification saying the 20th wire is not supposed to be connected (unless used for cable powered devices). If it is connected, then a 3.3V 500mA power is being supplied back into video card. This has weird, bad effects.