Problem w Dual Monitors on ATI Radeon HD 4870 512 MB

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Problem w Dual Monitors on ATI Radeon HD 4870 512 MB

Hi I'm having problems with Dual Monitors on ATI Radeon HD 4870 512 MB, Mac Pro 2009.

Setup: I'm running two 27" DELL U2713HM Displays at 2560x1440 one via direct DVI cable and the other one thru the Mini Display Port via Dual Link DVI adapter.

Now when I boot up the left screen displays the start-up apple as it should but then both screens go black and the right one (DVI connection) comes on while the left one stays black, goes into power safe mode. When I go into preferences > Displays I even get only one single display as if there were no multiple connected. It's however NOT a connection problem, since it works during the boot up sequence.

Any idea what might be wrong with my set-up? Do I need a new graphics card?

Mac Pro (Early 2009), Mac OS 8.6 or Earlier

Posted on Dec 24, 2014 5:14 AM

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Answer 1

lllaass

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Dec 24, 2014 6:49 AM in response to harald174

Which is the right one? Direct DVI? Or mini displayport>dual link DVI? You said both monitors are DVI connected.

Does the problem monitor work when the other one is disconnected?

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Answer 2

harald174 Author

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Dec 24, 2014 7:03 AM in response to lllaass

Yes the right one is connected via direct DVI. The Left one is using the mini displayport dual link! The monitors are working fine. I tested them and made sure they're ok!

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Answer 3

lllaass

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Dec 24, 2014 7:09 AM in response to harald174

So if you disconnect the direct DVI connected monitor the other monitor works fine via the dual-link connector?

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Answer 4

harald174 Author

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Dec 24, 2014 7:14 AM in response to lllaass

It works fine during the bootup seqence (grey apple) but then it goes black and nothing! No chance to do anything or waken the **** thing.

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Answer 5

lllaass

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Dec 24, 2014 8:13 AM in response to harald174

Again, what happens if yo disconnect the working monitor and they dry booting up with only the problem monitor connected.

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Answer 6

harald174 Author

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Dec 24, 2014 10:43 AM in response to lllaass

Exactly what I described above. It works fine during the bootup seqence (grey apple) but then it goes black and nothing! Even though it IS THE ONLY connected monitor!

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Answer 7

lllaass

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Dec 24, 2014 11:05 AM in response to harald174

You do have the dual-link adopter connected to USB power right?

Next I would try using a displayport to mini displayport cable. You monitors have:

Connectors VGA, 4 x USB 3.0, DVI-D (HDCP), HDMI, DisplayPort 1.2,

That cable is about $10

http://partnerdirect.dell.com/sites/channel/Documents/Dell-UltraSharp-U2713HM-Mo nitor-Brochure.pdf

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Answer 8

harald174 Author

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Dec 24, 2014 11:21 AM in response to lllaass

Ooohohh I figured it out. Thanks for your help I had USB connected, but I checked my connections, turns out one plug wasn't 100% inserted, works fine now. Thanks for your input!!! Deeply appreciated!

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