Phantom external display after disconnecting

Question

Level 1

0 points

Phantom external display after disconnecting

I have a 15" mid-2014 MacBook Pro Retina running 10.10.3. At my office I use it in clamshell mode, connecting two displays - one via thunderbolt to an external dock which breaks out to HDMI, and the other via a mini DisplayPort to HDMI adapter.

When I leave, I pull both connections (the computer is usually not asleep) but leave the MBP closed. I'm finding when I get home and open it again, it thinks one of the displays is still there (the one connected via the mini DisplayPort to HDMI adapter). I have tried putting the computer to sleep and waking it again, as well as forcing detect displays (holding option while in the displays system prefs). Nothing seems to affect it.

I'm sure a reboot would fix it, and I also could be more methodical about disconnecting at the office, but any ideas why this is happening and a way to prevent it or quickly force the computer to realize there are no external monitors?

Thanks!

MacBook Pro with Retina display, OS X Yosemite (10.10.3)

Posted on May 12, 2015 8:52 PM

Reply

Answer 1

sterling r

Community Specialist

May 14, 2015 2:44 PM in response to callmedavid

Howdy David,

From your post it sounds like your external monitor is still appears to be connected even though you disconnected it long ago. I'd recommend you do the troubleshooting in the following article to help you get the issue resolved:

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

This section in particular:

Reset the system

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

Reset the resolution

Start by resetting the Mac's parameter RAM. If the display does not come up, was previously set to an unsupported resolution, and still results in no video:

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.

All the best,

Sterling

Reply