11 Replies Latest reply: Oct 8, 2013 9:20 AM by gherth
trenchestrenches Level 1 Level 1

The studio where I work recently purchased a new Mac Pro, and since then, the 30" Cinema Display occasionally flickers. Sometimes very fast, sometimes not at all, sometimes once an hour, without any rhyme or reason. We switched out the display with another 30" and have the same problem. The tower is in a machine closet down the hall, and we use a long series of powered extenders to reach the display in the studio. This system has been in place for many years.


Here's a video of a particularly bad session:




Any thoughts? I would love to get to the bottom of this!

Mac Pro, Mac OS X (10.7.5)
  • The hatter Level 9 Level 9

    video card, model, and limits on dvi extenders come to mind as well as temp in closet

  • trenchestrenches Level 1 Level 1

    Thanks Hatter,

    The extenders and closet are unchanged from our previous setup, which has been in place and functioning normally for years.  Both 30" displays we've tried are fairly old; does anyone know if perhaps there's an incompatibility of some kind, or different power requirements or something?

  • Grant Bennet-Alder Level 9 Level 9

    The most likely failure is the graphics card, even if it has been working fine forever.


    You should seriously consider a newer graphics card. The Apple-firmware 5770 (about US$250) works in ALL model Mac Pros for everything except possibly minor issues with copy-protected movies.

  • trenchestrenches Level 1 Level 1

    Thanks Grant,

    The Mac Pro (and graphics card, ATI 5770) are brand new, everything else is older. This only began when we got the new tower. Maybe it was a bad card from the outset?

  • Grant Bennet-Alder Level 9 Level 9

    Is this coming directly off the DVI port, or using an adapter?


    Mini DisplayPort with an adapter is power-limited, and you should be using an ACTIVE adapter that has signal re-drivers.


    For a 30" display (which has a resolution above 1920 wide) you will need Dual-Link DVI all the way through: all cables, adapters and everything must be Dual-Link DVI (and all pins in the grid must be present).

  • trenchestrenches Level 1 Level 1

    We are using powered/active DVI extenders, connected to the DVI port. We also tried switching to the video card's Thunderbolt port and had the same flickering.

  • The hatter Level 9 Level 9

    You realize there are no Thunderbolt ports, only MiniDisplay.

    Only iMac and MacBooks have Thunderbolt.

    And not all dual link adapters are the same.





    Apple Mini DisplayPort adapters: Frequently asked questions (FAQ)


    Guide to Apple graphic display adapters needed


    Atlona (Dual Link) DVI to Mini DisplayPort Converter for Apple 27-inch LED and 27-inch iMac

    http://www.atlona.com/Atlona-Dual-Link-DVI-to-Mini-DisplayPort-Converter-USB-Pow ered.html

  • trenchestrenches Level 1 Level 1

    Sorry, Mini DisplayPort, my mistake. In any case, we're not using it now, we're using the DVI port.

  • Grant Bennet-Alder Level 9 Level 9

    Are any DVI extenders you are using rated for Dual-Link DVI? They require that three extra pairs of conductors be present (the three push-pull data lines are doubled) to support faster-than 1920-wide data.


    If you drop the resolution to 1920-wide and it perks up, Dual-Link is likley the issue.

  • trenchestrenches Level 1 Level 1

    That's interesting, Grant. I tried dropping the resolution but to no avail. As an experiment I just swapped out the graphics card with an NVIDIA from a different computer and so far, no flickering. But it's always been unpredictable so we'll see...


    Thanks for your help everybody.

  • gherth Level 1 Level 1

    I am on my third Mac Pro since last year and have the same issue with each system.  The first two Mac Pro's were mid 2010, and the last one is 2012.  All have the Radeon HD 5770 standard graphics card attatched to a 2005 Apple 30" HD Cinema Display, no adapters, all original cables.  Display flickers intermittently upon power up; only fix is to shut down and power up again.  Apple refuses to admit that there is an issue with this graphics card.  I have never had this issue with a 2005 Mac Pro attached to the 30" display.


    Just got off the support line with Apple;  need to take tranqualizers, very infuriating.  First question after I tell them this is my THIRD computer with the same issue;  Are you sure the cable is connected correctly?


    First level ******** buffer sent me to 'senior level tech support' with ne better result.  Two choices: take it in to the Apple Store whose employees broke in to my administrator acount on Mac Pro number 2, or refer to engineering and possibly have a 'third party' tech come to my location and replace graphics card if engineering approves.


    It is my own fault for using products made in china.  What else should I expect!