Multiple Displays Crashes with El Capitan My dad has a Mac Pro (2009 era) and runs 3 monitors hooked up with DisplayPort. They are not high-res and only about 24". Nothing that a Mac Pro should have any issues with. Everything worked well until he upgraded to El Capitan last week. Almost immediately, it crashed to the login screen. I spent a while troubleshooting the problem and all of the crash reports point to graphics problems (which seems apparent). Right now, he is down to one monitor to mostly rule out the crashes. I found that disabling "each display on it's own space" helped, but if he is working with one display and a notification comes in on the other one, it will consistently crash. 

I'm not sure what else to try. Is there a way that we could get him back up to the three monitors? I understand that these problems could point a potential graphics card problem, but I don't think that is the problem considering the direct correlation to the OS upgrade and the crashing. I also haven't been able to find others with similar problems.

I have tried:


Multiple Reboots
Disable: "Preferences -> Mission Control -> Displays have separate Spaces"
Disable: "Preferences -> Mission Control -> Automatically rearrange Spaces based on most recent use"
Confirm that "Automatic Graphics Switching" didn't exist on his machine
More reboots
This problem is well documented on the Apple forums. For the moment, until the next release of El Capitan, you can only run two monitors. The monitors must be connected to one video card. You do not have to remove the other card.

Please search the Apple forums for more details.