Mac Pro Multi-display Configurations

Discussion in 'Mac Pro' started by A_L_Koide, Apr 28, 2016.

  1. A_L_Koide macrumors newbie


    Apr 28, 2016

    I am having quite a bit of difficulty getting my 3-display system to work properly on my MacPro 6,1 and I am wanting to know anyone has more information on this type of setup.

    I have been through the official Apple document numerous times and have since taken the computer into an Apple store for the 2nd time in the short time I have had it. It was purchased in June of 2015. The first take in was to troubleshoot the intermittent video issue that Apple finally made an announcement about recent but this was resolved by having one of the video cards (Dual D700s) replaced.

    The issue I am having now is that I can get any pair of my three displays to work but not all three simultaneously. Here is what I have and maybe someone can tell me if this will or should work on my machine:

    1) Vizio 4k UHDTV - HDMI
    2) 27" LCD HD - HDMI w/ MiniDisplay Port Adapter
    3) 27" LCD HD - HDMI w/ MiniDisplay Port Adapter

    The Apple document does state "two HDMI displays with one connected via minidisplay port" or something to this effect. I am trying to understand why my configuration does not work if indeed I am limited to only two HDMI display despite my having the adapters.

    Based on my most recent discussion with the "genius bar", they appear to be blaming my configuration for the issue and have cited the Apple document. I have already tried every display on every bus and verified them as good / functional along with the adapters themselves since I never swapped or moved them. I have attempted to resolve / mask the issue by performing a Safe Boot and also booting to separate install of OS X but both of these failed to turn on the 3rd display.

    I can accept that this may be a configuration problem but I would like to have a better understand of first what causes the limitation on such a supposedly high-end computer and secondly what pair of monitors should I purchase in order to have a working triple-display setup. Apple appears to be the only one making thunderbolt displays and all of the recommended UHD monitors from various articles do not have mini displayport connectors so I am assuming I will also need a different set of adapters.

    On a final note, something I noted and provided to the Apple store is that I could never have a display listed under the D700 in PCIe Slot-1 regardless of which pair of displays had video during my troubleshooting. Does anyone know if this is normal?

  2. ActionableMango, Apr 28, 2016
    Last edited: Apr 28, 2016

    ActionableMango macrumors G3


    Sep 21, 2010
    All of the video outputs are connected to one video card. The other card is used for compute purposes only, so it is normal and expected to see all displays connected to one card. In fact in many use cases that second card will never be used.

    One very strong possible source for your display problem are your adapters, which you do not describe with sufficient detail. This AMD card only supports up to two legacy connections at a time, and you have three (HDMI is a legacy connection). You can get around this restriction by using an active adapter. So at least one of your adapters must be an active adapter, not a passive one.

    Unless you are certain that at least one of your adapters is an active adapter, then I strongly suspect that is the problem, and I'd try an active adapter. Apple's active adapters are problematic and typically only work well with Apple's displays, so I'd get a third party active adapter from a trusted source such as

    Just to be clear, you do not need three active adapters. The AMD card supports two legacy displays, so the first two can use the less expensive passive adapters. The third legacy connection (HDMI, DVI, VGA, etc.) and all additional legacy connections after that must have active adapters.

    If you want to know more about legacy connections and active/passive adapters, see my post here.

    On the other hand, the Apple Genius should definitely know this, so it's possible that he checked your adapters, that they are okay, and that you have some other, more atypical problem.
  3. A_L_Koide, Apr 28, 2016
    Last edited: Apr 28, 2016

    A_L_Koide thread starter macrumors newbie


    Apr 28, 2016
    Thank you!!! Do you happen to have a direct link to any of the active adapters that you would personally recommend? They do not have my adapters at the store. They are absolutely the problem.

    And the other question is, after reading the other thread, how many non-legacy clocks are there on the D700 video cards?
  4. ActionableMango macrumors G3


    Sep 21, 2010
    I have no personal experience with adapters at all, so I hesitate to recommend anything. I have only ever run two monitors at most.

    The following looks like it would work, but I repeat, I have no personal experience with it:

    It is active, supports 4K, adapts MDP/TB to HDMI, has good reviews, and comes from a retailer with a good return policy in case it's wrong or doesn't help.

    The way Amazon links work though, you never know which "size" will pop up for others when they click the link. So make sure the "size" is set to HDMI, not DVI.
    --- Post Merged, Apr 28, 2016 ---
    It just occurred to me... if any one of your monitors or TV has a Display Port or Mini Display Port, you should just use a cable for that instead of an HDMI cable. Then you won't need an adapter at all.
  5. A_L_Koide thread starter macrumors newbie


    Apr 28, 2016
    Got my active adapters in and it worked! Thank you so much for the help!

    Attached Files:

  6. carylee2002 macrumors member


    Jul 27, 2008
    I have 2 nvidia quadro cards and running a 27" cinema display and 3 Hp lp2480zx monitors via displayport connections.

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