Dual monitor issues after upgrading OS X

I have a macbook pro 15" mid 2009, 2.66GHz, 8GB RAM, with a NVIDIA GeForce 9600M 256MB graphics card. I am connecting it to a second monitor that is a Cinema HD LCD monitor that requires an Apple Mini Display Port to Dual-Link DVI adapter. The Cinema display is set as the main screen and mirroring is turned off.

After upgrading to Yosemite I started having trouble with the video on the mbp becoming scrambled as I work on the other monitor. I let it go for a while thinking it would be something Apple would fix in an update but no such luck so far.

Typically I will use the Cinema display for my main work and use the mbp screen for either photoshop pallets, to-do list, email, etc that I use to support the work I am doing at the moment. What happens is as I work, especially as I switch between windows, the display on the mbp becomes a garbled jumble of partial images from the open windows on the main screen. Sometimes if I move my mouse over the mbp screen it will redraw portions of the image that should be on the screen, and when it shows me a title bar I can grab it and drag it around the screen and it will redraw the screen as the open window moves around. (Think of the open window as an eraser that removes the garbled mess.)

Interestingly, if I do a screen capture of the garbled screen, the image is clean and as it should be, all while the screen that I physically see still has the garbage on it.

I am attaching three images. One is the screenshot of my display details, one is a screenshot of the mbp screen showing what it SHOULD look like, and the third is a cell phone pic of what it actually looks like.

I would assume that the video card can't handle the old Cinema display in a dual monitor situation, perhaps even that there wasn't enough video ram to handle it. Except for the fact that it ran fine for years before I upgraded to Yosemite.

Any suggestion on how to resolve this issue would be greatly appreciated.

Doug

There could be several issues going on. The fact you can do a screen capture of the MB Pro's screen when it is messing up yet the picture comes out looking perfect makes me wonder if there might be a loose or pinched cable going to the LCD display on the MB Pro.

A few questions:

1. Did you do a clean install of Yosemite? Is it currently 10.10.4?
2. Does the MB Pro monitor mess up if it is not connected to the other monitor?
3. Is it possible to re-install Mavericks to see if that fixed the issue?

Lisa

There could be several issues going on. The fact you can do a screen capture of the MB Pro's screen when it is messing up yet the picture comes out looking perfect makes me wonder if there might be a loose or pinched cable going to the LCD display on the MB Pro.

Click to expand...

I agree with Lisa, and also check your dual link DVI adapter and any other cabling between the monitors.

Definitely not a cable problem on the mbp, it works fine whenever it isn't hooked up to the Cinema Display.
Yes it is OS X 10.10.4
Yes, I can reinstall Mavericks, it worked fine on previous OS's for about three years. I would prefer not to have to revert to an old OS.
I do not have extra Dual-link DVI cables to test with, but since it did work properly previous to the upgrade with these same cables I do not suspect them as the cause. If they were having problems then it would be more likely that the Cinema display would be the screen with the jumbled mess.



Ok, so thinking about all the different ways I have used this mbp with external monitors and projectors I came to the realization that the Cinema display is probably the only one that I had set up as the Main screen while making the built-in screen the secondary display. So I did a test and changed the built-in screen to be the main display and it has worked for three days now without becoming jumbled a single time. This doesn't resolve the issue, but it is a workaround that I can live with.

Thanks for taking the time to reply!
Doug