Dual displays - Mac Pro - Snow Leopard

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Level 3

696 points

Dual displays - Mac Pro - Snow Leopard

I'm trying to set up dual displays for the first time ever. I have a Mac Pro 2.66 Quad-Core, OS 10.6.4, ATI Radeon HD 4870. My display is an older (but still perfectly fine) Apple Cinema HD 23" display.

Today I purchased a Dell 23" LED monitor and have connected its HDMI output to the Radeon's Mini DisplayPort with an adaptor, and am completely unable to make things work. I spent quite a bit of time with Dell and they swear that the display is fine, but I'm still stuck.

When I connect the Dell, the Dell does nothing, but the Cinema Display changes to show only the splash screen that comes up when you first log in....except there aren't accounts from which to choose...only the splash screen. I see my mouse moving around on the screen, but can't get anything else to show up on the screen know matter how many key combinations I try. If I disconnect the Dell, the Cinema Display returns to normal.

Dell had me diconnect the Cinema Display and use only the Dell....nothing. The light on the Dell indicates that it's getting power, but pushing the power button on the screen doesn't do anything.

I figured out that, when both monitors connected, I can push the display button on the Cinema Display and get to the Displays preferences screen. At first, I see only the Display Preferences window exactly as it's always looked, but when I "gather windows" I get two windows...one is the usual window for the Cinema Displa with the Display, Color and Options tabs. The other is for the Dell and this one has the added Display, Arrangment and Color tabs.

When I play with the options in the Cinema Display window, it behaves like it did when there's only one display and the Dell window disappears. When I play with the options in the Dell window, the Cinema Display looks distorted....apparently the Dell settings are being applied to the Cinema Display. When I'm in the Dell window and go to the "Arrangment" tab, I see the two images repesenting the two monitors. I can move those around in the manner described in the Mac documentation....that affects the Cinema Display and can move things off the screen, but the Dell remains black and silent. When I select the "Mirror" button, the two images in the Display window are stacked on top of each other....both with a menu bar at the top of their windows. The Cinema Display looks like normal, but again, the Dell remains black.

I have no clue what to try next. The Dell has never turned on, though it IS receivne powerl Help?

2.66 Ghz Quad-Core, Mac OS X (10.6.2), 8 GB 1066 MHz DDR3, Apple Cinema Display

Posted on May 7, 2012 11:06 PM

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Answer 1

Best reply

X423424X

Level 6

14,265 points

May 7, 2012 11:35 PM in response to Bryce Inman

I'm a little confused at what you are seeing.

1. Options tab? What Options tab? The possible tabs are Display, Arrangement, and Color. I don't know what you are referring to about an Options tab.

2. Arrangment tab is on the Dell? Is that defined as your main monitor, i.e., the one with the menu bar. In the Arrangment window the image of the screen with the little white menu bar is the main monitor. You can drag that to either monitor to define that monitor as the main monitor.

Have you played with the resolution and refresh rate (if present) of the Dell?

Did you click Detect Displays?

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Answer 2

Bryce Inman Author

Level 3

696 points

May 7, 2012 11:50 PM in response to X423424X

1. When I select the Display Preferences, I see three tabs....#1 DISPLAY: Resolutions, Rotation, Brightness, Gather, Detect. #2. COLOR: Several profiles listed. When I select "this display only" I see two separte Apple Cinema Display profiles and one that just says "Display." Others listed are Adobe RGB, Apple Cinema HD Display Calibrated, Generic RGB Profile, HP 2311 (that's my new display) and sRGB blah, blah. #3 OPTIONS: Two things to toggle....Disable power button and Disable display preferences button.

2. The Cinema Display is the main monitor in the Dell window. I didn't do anything to select this, but when I click on the main (larger) display, I see a red line around it and a red line appears on my Cinema Display.

Yes, I've played with the resolution....I've played with all the options.

Detect Displays was the first thing I did when I connected the Dell....seemed like the obvious thing to do.

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Answer 3

X423424X

Level 6

14,265 points

May 8, 2012 12:22 AM in response to Bryce Inman

1. When I select the Display Preferences, I see three tabs....#1 DISPLAY: Resolutions, Rotation, Brightness, Gather, Detect.

Oh we have a semantic problem which led to my confusion. The "tabs" are the display, arrangement, color items. The rotation is a "popup menu". The Gather Windows and Detect Displays are "buttons". Brightness is a "slider".

#3 OPTIONS: Two things to toggle....Disable power button and Disable display preferences button.

Must be specially added because of the dell which is why I am not familiar with it.

2. The Cinema Display is the main monitor in the Dell window. I didn't do anything to select this, but when I click on the main (larger) display, I see a red line around it and a red line appears on my Cinema Display.

Something is not right here. The Arrangement defines the spatial relationship of the two monitors. You can slide one around the other in the Arrangement to define their orientation relative to each other. If the Dell is to be on the left and the cinema on the right then slide them that way in the Arrangement.

The red outline should only be on one monitor at any one time when you click that monitor in the Arrangement. If you click one of the monitors in arrangement and see the red outline around both monitors then that is one of your problems. That should not happen.

Another thing is the fact that the Displays window with the Arrangement tab came up on the Dell even though you have the cinema defined as your main monitor.

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Answer 4

Bryce Inman Author

Level 3

696 points

May 8, 2012 10:24 AM in response to X423424X

I talked with Apple Support this morning. The first development was that, when I lifted the Dell to look at some of the buttons, it suddenly kicked to life. I have no idea what I did, but something jostled and made the connection.

After that, I learned that I was misunderstanding some basic concepts of how the monitors behave in both extended and mirroring modes....too much to explain here.

Since monitors share the same resolution chosen while in mirroring mode, that isn't going to work for me, though that's really what I wanted to do....there just isn't a single setting that works well for both screens.

Everything's running, I just need to play with the settings for a while. Thanks for your help.

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