2 ATI Radeon HD 5870s?

Discussion in 'Mac Pro' started by centauratlas, Aug 10, 2011.

  1. centauratlas macrumors 6502a

    centauratlas

    Joined:
    Jan 29, 2003
    Location:
    Florida
    #1
    Hi,
    Does anyone know if you can put two ATI Radeon HD 5870s on the Mac Pro 2010 (MacPro5,1)?

    Thanks!
     
  2. ActionableMango macrumors 604

    ActionableMango

    Joined:
    Sep 21, 2010
    #2
    Yes but each card requires two power leads, for a total of four, and the MP only provides two. You need to supplement the power with a secondary internal or external power supply.

    Also, Crossfire will not work in OS X and it looks like Lion is having some problems with dual video cards in general.
     
  3. centauratlas thread starter macrumors 6502a

    centauratlas

    Joined:
    Jan 29, 2003
    Location:
    Florida
    #3
    Thanks. :)

     
  4. centauratlas thread starter macrumors 6502a

    centauratlas

    Joined:
    Jan 29, 2003
    Location:
    Florida
    #4
  5. ghislain macrumors member

    Joined:
    Apr 22, 2009
    #5
    each PCIe slot delivers at most 75 W, so that you get at most 150 W for the 2. By splitting these 2 slots between your 2 cards, each will receive at most 75 W, i.e. 150 W when added with the PCI slot supporting each card. Considering that 5870 cards require 180 W to function properly, you see that they will be under powered. This may work but at the cost of stressing PCIe slots and probably running 5870 in an energy saving mode; i.e. with poor performances. If you wish to run 2x5870 at full speed, you really need an external PSU. In other forums, procedures are described to power on and off such extra PSU when MP is on or off..
     
  6. Cindori macrumors 68040

    Cindori

    Joined:
    Jan 17, 2008
    Location:
    Sweden
  7. ghislain macrumors member

    Joined:
    Apr 22, 2009
    #7
    Indeed, the "Mac Bidouille" trick works (I used it for a while). However, in Bootcamp Win7, the 2x5870 in crossfire mode didn't work at full speed, so there was very little improvement when tested with 3DMark06. Now, with an external PSU and the "relay trick", there is about a 50% increase as compared to a single 5870. Of course, under OSX where graphic cards are generally much less stressed, the "Mac Bidouille" trick might do the job...
     
  8. Spacedust macrumors 6502a

    Joined:
    May 24, 2009
    Location:
    Poland
    #8
    I use 2x HD5770's - one Apple and one flashed XFX.

    Crossfire works under Windows without any problems but only on Catalyst drivers up to 10.11.

    MAC OS X Lion works fine with two cards.

    Installing genuine Apple card unlocked PCIe 16x 2.0 on the flashed XFX card :)
     
  9. ghislain macrumors member

    Joined:
    Apr 22, 2009
    #9
    In this post, I forgot to mention that, according to the "Mac Bidouille" trick, additional power supply was delivered by one of the 4 HD SATA slots. However, these slots are designed to deliver 5 W (25 W for the full HD line) and saturate at 32 W, whereas 60 would be required to fully feed the two 5870. Therefore, I still would not recommend this method that may work with 2x5770 which probably require les power...
     

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