Three monitor setup on the Apple Radeon 5870

Discussion in 'Mac Pro' started by akadmon, Apr 23, 2013.

  1. akadmon Suspended

    Joined:
    Aug 30, 2006
    Location:
    New England
    #1
    I just bought an NEC PA271W (2560x1440) to compliment my 30" ACD a Dell 2407 (1920x1200). I have the ACD on the DVI port and the other two on the Mini Displayports. Only the ACD and one of the other two monitors are live.

    What am I missing? Is the card not caple of supporting three displays? If that's the case, why the heck does it have three inputs!? :confused:
     
  2. bernuli macrumors 6502

    Joined:
    Oct 10, 2011
    #2
    My understanding is you can do 3 but cannot use adapters. So the ACD in to the DVI, then the other two using Mini Display to standard Display Port connectors.

    Is that what you are doing now? You might be pushing it though with the 27" monitor.

    I would like to do something similar but have not been able to find the Mini Display Port to straight up Display Port.


    B
     
  3. akadmon thread starter Suspended

    Joined:
    Aug 30, 2006
    Location:
    New England
    #4
    Thanks for the link.

    The 27" NEC (I am surpsised by how small it is compared with the 30" ACD, BTW) came with a mDP cable, so its direct connected to the card. The 24" Dell doesn't have a Displayport output, so I'm forced to use a DVI-->mDP adapter (single link). I don't understand why an expensive dual link DVI to mDP adapter is required for it. I thought this type of adapter is only required for 27"+ displays.
     
  4. Bwa macrumors 6502

    Joined:
    Jun 20, 2007
    Location:
    Boston & San Jose
    #5
    You will need the active adapter to connect 3 displays, even if one of the DisplayPort-->DVI devices is a smaller resolution, such as 1600x1200. It's a limitation on the card side (I forget the details). It can do it -- I have driven 3x30" from a 5770, with two of Apple's active ($99) adapters.
     
  5. akadmon, Apr 23, 2013
    Last edited: Apr 23, 2013
  6. bax2003 macrumors 6502a

    bax2003

    Joined:
    Dec 25, 2011
    #7
    Those active adapters are for 1920x1200 or lower resolution, just a warning.
     
  7. akadmon, Apr 24, 2013
    Last edited: Apr 27, 2013

    akadmon thread starter Suspended

    Joined:
    Aug 30, 2006
    Location:
    New England
    #8
    That's all I need for my 24" Dell.

    UPDATE:

    The Startech cable I linked to in post #6 doesn't work at all. Could be just a faulty unit, but I'm not getting a second one just to find out. I'll try the Apple adapter next, though it seems silly to spend $100 on a cable, just to connect an old monitor that is probably worth not much more than that.
     
  8. akadmon thread starter Suspended

    Joined:
    Aug 30, 2006
    Location:
    New England
    #9
    UPDATE

    I bought the Apple DL DVI-->mDP cable and found it to be flaky. The signal on the third monitor keeps dropping out every few minutes, requiring the monitor to be power cycled. Today I got a Sapphire active DVI-mDP adapter (max 1920x1200, but a quarter of the cost of the Apple cable) and so far it's been flawless. Woohoo!
     

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