D300 nMP 3rd display issue

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Just setting up my nMP - base model. I have two 24" Apple Cinema Displays and one Dell 24" Ultrasharp. All three using DVI to Mini Display adapters. I can get any two displays working, but the third stays black. Any combination of two works, the third doesn't. The thunderbolt ports used doesn't seem to matter.

Thoughts?

 

[ApfelKuchen]

Per http://support.apple.com/kb/HT5918

You can use two DVI displays with your Mac Pro. If you connect a third display via HDMI, it will cause one of the three displays to become inactive. To avoid this, consider using Thunderbolt, Mini DisplayPort, or VGA for connecting additional displays if you are already using two DVI displays.

 

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I remembered that diagram from another thread, but wasn't finding it.

Thanks for the help!

 

[MacVidCards]

Depending on which Dell 24" you have, it may be DP capable.

I have a U2410 that has DisplayPort.

Another option would be active MDP to DVI adapter. Apple sells one as do some other vendors.

Last choice would be to use VGA into the Dell.

You will find color and clarity reduced if you go this route.

 

[thekev]

Seconding what Macvidcards said (btw welcome back) displayport should always be your first choice if your gpu supports thunderbolt, mini displayport, or displayport out, and it's included on the back of your display. I try to avoid adapters wherever possible. In the case of thunderbolt or mini displayport to a displayport display, I would say try a mini displayport to displayport cable. I have one that I ordered from a display oem, but the ones on monoprice should work fine. It's a bit more elegant and less likely to fail than an adapter. Aside from my personal experience with both, I've compared reviews.

 

[demars]

Another option would be active MDP to DVI adapter. Apple sells one as do some other vendors.

This would probably solve the problem. The Apple adapter is quite expensive since it is dual link DVI to DisplayPort; if you don't need dual link DVI then there are much cheaper adapters. I have a Radeon 5770 that has a similar restriction but I get around it by using Accell active adapters which sell for about $30 and there are some other brands that are even cheaper.