Dual Displays switching sides on reboot

Question

Level 1

10 points

Dual Displays switching sides on reboot

Hello,

I have the 2.7 Intel Core i7 released this past July running 10.7.2 with two identical Dell 24" monitors.

The monitor on the left, with the Dock, is hooked up to the thunderbolt port with a MDP/Thunderbolt to DVI adapter and the second monitor on the right is using the HDMI port and hooked up with an HDMI cable. When everything is working properly I can simply drag a window from the left monitor to the right monitor.

Whenever I reboot and the Mac comes back up to the login screen the monitor that is physically on the right is now displaying the image that should be on the left and vice versa for the monitor on the right. The only way to correct this is to pull the cable out of the MDP and plug it back in, and when I do that the right monitor is on the right and the left is on the left.

I have tried shutting down and holding CMD+Option+P+R with the same results.

Any suggestions?

Mac mini, Mac OS X (10.7.2)

Posted on Jan 30, 2012 2:04 PM

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Answer 1

den.thed

Level 9

77,176 points

Jan 30, 2012 4:38 PM in response to bradqe2

How is it setup in the Arrangement tab of your Displays preference, with the main display on the right or left?

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Answer 2

bradqe2 Author

Level 1

10 points

Jan 30, 2012 6:58 PM in response to den.thed

In system pref., the main display is on the left, both before and after rebooting. But after a reboot the main display is now on the right and the second display is on the left, eventhough system preferrences shows otherwise.

If I pull out the MDP/Thunderbolt cable from the Mac Mini and then reconnect, the main display returns to the left.

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Answer 3

den.thed

Level 9

77,176 points

Jan 30, 2012 7:10 PM in response to bradqe2

Swap the cables to the displays and then reset the main display to the left display.

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Answer 4

bradqe2 Author

Level 1

10 points

Feb 4, 2012 6:25 AM in response to den.thed

I think I finally have it. I wasn't as simple as swapping the cables.

First I made sure all three users were logged out. Logged in to each user account and set monitors to "mirror" and logged off of each user. turned off each monitor, swapped the cables.

Reboot

Logged into the Admin account, set that user to dual display with the MDP on the left

logged out

Logged in to the other two user accounts and set dual display with MDP on the left.

I've rebooted a few times now and each time the MDP monitor is on the left with the HDMI on the right, and they haven't 'swapped' positions.

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Answer 5

link6009

Level 1

5 points

Feb 14, 2013 5:43 PM in response to bradqe2

I think I have found a solution to this pesky problem...

I believe the reason this problem is happening is because both monitors are using the same color profile.

GO to: System Prefs/Display/Color and take a look at the profiles for each monitor. If they are set to the same profile, that's your problem right there.

By simply setting them to different profiles, I got rid of the dual monitor-switching problem at reboot.

Try it, and let me know if it works for you as well...if so, I'll have to congratulate myself ...for the first ever technical contribution I've made to others on the internet!!

Cheers!

Link6009

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Answer 6

link6009

Level 1

5 points

Feb 25, 2013 1:33 AM in response to link6009

I hate to burst my own bubble here, but I recently added a 3rd monitor, and now I'm getting the same inconsistent monitor switching between my second and third monitors.

Here's my set up:

Mac Pro, OSX 10.8.2

2x2.26 GHz Quad Core Intel Xeon

16 GB RAM

Three Dell ST2420L display monitors

What seems to be happening now is that I get three identical 'color' display profiles. The first one seems to stay on the same monitor, but the second and third monitors now switch at random. I can't seem to get them to stay in any particular order.

Any suggestions or new approaches for solving this would be greatly appreciated!

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