Dual Monitor Question

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Dual Monitor Question

Hello all,

This is more of an annoyance than an issue but I wanted to bring it up to see what others thought.

I have a Mac Pro with two NVIDIA GeForce GT 120 512 MB video cards in it and I have two 24-inch Cinema displays (one per video card using thunderbolt connection). Every so often one of the monitors will go black for one or even less than a second but the other monitor is fine and never goes black.

I wasn't sure if this was something to do with the monitor itself or the video card it's plugged in to.

Any feedback would be great.

Thank you,

Matt

Mac Pro, OS X Yosemite (10.10.1)

Posted on Jan 15, 2015 8:21 AM

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Answer 1

Nubz N.

Community Moderator

Jan 17, 2015 7:47 AM in response to coombsm

Howdy coombsm,

You could swap the displays and see if the issue follows the display or stays with the video card.

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

Check connections

When using an external display be sure to check the following:

If you're using an Apple notebook, confirm the AC power cable or adapter is securely connected to the computer and the cable providing power to the display is also secure. It is always good to have your notebook connected to AC power when an external display is in use.

Confirm display adapters are fully seated in their respective connections and that they are supported models and for the computer and display. Refer to these articles to assist you with adapter compatibility and further configuration information:

Monitor and Display Adapter Table

About Mini DisplayPort to HDMI adapters

Apple Mini DisplayPort adapters: Frequently asked questions (FAQ)

Thunderbolt ports and displays: Frequently asked questions (FAQ)

Remove all display cable extenders, KVM switches, or other like devices and retest to determine if the issue is resolved.

Try unplugging the video adapter or cable and then plug it back in.

If more than one video adapter is in use (or "daisy-chained"), troubleshoot by using only one adapter.
Example: A mini DisplayPort to DVI adapter connected to a DVI to HDMI adapter is an unsupported configuration because there is a series of adapters in use.

If available, try using a different display and or adapter (or use a different connector by using DVI instead of VGA, for instance).

Then go from there.

Nubz

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Answer 2

The hatter

Level 9

60,990 points

Jan 17, 2015 8:07 AM in response to coombsm

Just a small footnote: you don't have Thunderbolt cables or monitors, you are using Mini Display Port.

Instead of using two GPUs which don't really buy you anything unless you run 3 or 4 displays, you might want to upgrade to a more current AMD or GTX with more VRAM and support.

You would need a Late 2013 Mac Pro 3,1 to use Thunderbolt.

At one point support for dual GT120s was missing from OS X Mountain Lion. If you have been upgrading your system all this time without a clean install, Yosemite should be when you do. Quite easy, and great point in time to do so to a new SSD device as well.

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