for 3rd display: do I need another graphics card?

Discussion in 'Mac Pro' started by malch, May 2, 2011.

  1. malch macrumors 6502

    Jan 20, 2008
    Hi there,
    I have the 6-Core MP, which came with the ATI 5870 graphics card. I now want to add a third display. I've read other threads about this, and some people say I can easily run a third display with the one card I already have; other people advise getting a second card.

    I'm a video editor, not a gamer, which I mention in case it makes a difference. I need the third display just so I can see more bins, and maybe also whatever script I'm working with.

    So... do I need a second card to run a third display?

    If I do... Tansporteur said: "For about 100 bucks or less (depending on the which exact Pro you have) you can get an additional graphics card that drives two 2560x1600 displays". What card might he be referring to? On the site, a 5870 is $479!!!

    Thanks for any advice,
  2. Jbgloss macrumors member


    Feb 20, 2011
    Fort Lauderdale, Florida

    I have a six core with a 5770 and I was running 3 two ACD's and one Samsung via DVI - no issues at all - It depends on the CONFIG. I got rid of the Samsung and I am using the 2 ACD's going to buy another 5770 for my third ACD.... It will not work with 3 ACD's from my understanding.

    I believe you can ONLY RUN 2 ACD's and the Third DVI - You can't run 1 ACD and 2 others.

    What type of monitors do you have? That is the key....

  3. malch thread starter macrumors 6502

    Jan 20, 2008
    I currently have two Dells (sorry, Apple, but I needed matte not glossy):

    - a U2711 (2560x1440) and
    - a U2311H (1920x1080)

    If I get another it would be another 23" Dell (the U2311H), so, another 1920x1080.

    So does this mean I could get by without having to buy another graphics card?
    If I do, would this slow everything down noticeably?

  4. ActionableMango macrumors G3


    Sep 21, 2010
    Yes there is confusion about whether the cards will support up to two or up to three.

    The Eyefinity FAQ explains this:

    How many non-DisplayPort monitors can I use with an AMD Eyefinity technology-enabled graphics card?

    You can connect up to two non-DisplayPort monitors at one time to an AMD Eyefinity technology-enabled graphics card using non-DisplayPort connections or passive DisplayPort dongles. To enable and drive 3 or more non-DisplayPort monitors at one time, the additional non-DisplayPort monitors must be connected with an active DisplayPort dongle.

    So you can do three monitors, but at least one of the monitors needs to have DisplayPort or you'll need an active adapter for it.
  5. Cindori macrumors 68040


    Jan 17, 2008
    to run 3 displays with apple 5870 or 5770, you have to connect one of the displays with DP.

    If no display has DP connector by default, you need to buy an active adapter which is like $90.
  6. malch thread starter macrumors 6502

    Jan 20, 2008
    Cindori — this sounds good, because one of my two Dells is connected via DP (I had to get a small DP to mini-DP adapter). The other is connected with a bigger connector (I think it's called VGA).
    There's one DP port still free on the back of my Mac Pro. Should I connect my third Dell to this?

    Mango — I'm not sure from your post if I need to worry about this or not. I'm not using an AMD Eyefinity graphics card. I've got the ATI 5870. But maybe you're saying that my ATI card is "AMD Eyefinity technology-enabled".
    Not sure about this, but I'm hoping that Cindori is correct, and I can simply attach a third Dell via DP.

    I'll be really pleased if I don't have to buy another graphics card!
    Thanks so much, malch
  7. alust2013 macrumors 601


    Feb 6, 2010
    On the fence
    No need for another card. You have one connected with MiniDP to DP and the other via DVI, from what it sounds, so you could simply hook up the third via miniDP to DP again, and you'll have no issues. Not sure where you bought your original miniDP to DP cable, but has them for very good prices.

    Should you decide you need 4 or 5 monitors, the graphics card Transporteur was referring to was the GT120, which is super cheap and small.
  8. Cindori macrumors 68040


    Jan 17, 2008
    nvm, it seems I cant remember stuff i've said before

    the 5870 has 2 DP ports and means 2 DP connections must be made.

    But yeah, if u got 2 DP monitors, you're set.

    I don't know what you mean by "two are connected by dp" and "there is still one dp port left".

    big port its not VGA, its DVI.
  9. ndraves macrumors member

    Jan 19, 2011
    Having been through this with the 5770 (same as far as 3 screens go) I'd clarify all the above with:-

    You already have 1 screen connected to the DVI port on the card (big white one)

    You have another connected to the Mini DP with a MDP - DP adapter

    So for another screen on the same 5870 card then if the new screen has a DP input then another MDP - DP adapter and you're off!

    If the new monitor only has a DVI input then the adapter from the MDP - DVI MUST be an active adapter. A simple adapter like the Apple one for $29 will not work (only 2 screens will). For the active adapter then you will be fine with 3 screens.
  10. malch thread starter macrumors 6502

    Jan 20, 2008
    as Cindori said: "big port its not VGA, its DVI", and as ndraves made even more clear: "You already have 1 screen connected to the DVI port on the card (big white one)". The colour-coding helps!
    I'm all clear on this now, and I now know I can connect another display, via DP (to mini-DP), and it'll work. Fantastic, and thanks so much...
  11. ActionableMango macrumors G3


    Sep 21, 2010
    Ignore the Eyefinity branding. The FAQ is just saying the same thing Cindori is, which is all three cannot be passive. At least one of the three has to be DP or an active adapter. The other two can be DVI or VGA.

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