Dual ATI 5870's in early 2009 Mac Pro

Discussion in 'Mac Pro' started by Skrjabin, Jun 16, 2011.

  1. Skrjabin macrumors newbie

    Jun 16, 2011
    Hey everyone,

    I'm not writing to ask whether it is possible to put two cards into a Mac Pro, which it is. (A little research will show people doing it.) But my question is this:

    I have a Mac 5870 right now, and my hope -- since my computer is multi-purpose -- was to throw in another 5870 to run Crossfire in Bootcamp. I know OSX does not support crossfire, so I'm really only considering this purchase for gaming in Bootcamp Windows 7 64.

    My question then is ...

    Do I need to even buy the (Way overpriced) "Mac" version of the card for use in windows? From what I gather, the card should read in windows just fine if it is a PC card, OSX would just boot using the already existing card, and I'll get the best of both worlds.

    I'm not a incredibly saavy tech guy, but, are there any loopholes in my logic here? Will the PC 5870 be able to crossfire with the Mac 5870? I don't see why not, but, again, I'm not knowledgable enough to make this call.

    Any help would be greatly appreciated!!!

    Setup is:

    Mac Pro Early 2009 2.26 8 core
    Ati 5870 1 gig
    16 gigs of ram
  2. ActionableMango macrumors G3


    Sep 21, 2010
  3. nanofrog macrumors G4

    May 6, 2008
    So long as the Crossfire bridge locations are there (notches and contacts in the card PCB), then all you'll need is the actual Crossfire Bridge connector and necessary Windows drivers. :)
  4. neem' macrumors newbie

    Jun 16, 2011
    I for one encourage you to find out, because if it works, I'm doing it. I doubt my 4870 will be up to the task of Battlefield 3 at 'E3 stage demo' settings, and my PS3 certainly won't. I don't see why the Mac card would deliberately remove the necessary connections, but I'm with nanofrog on this.

    I'm half considering leaving the 4870 in, getting a 6970 as well and working out how to: Power it, get OS X to ignore the 6970 and get Windows 7 to ignore the 4870... At least from what I've read a card that isn't supported in Mac OS should still work through Boot Camp.

    Oh, and of course, I need all that power for my graphics and coding work. In fact I might get into 3D rendering to justify a massively powerful GPU.
  5. nanofrog macrumors G4

    May 6, 2008
    As OS X doesn't support it, it's possible. But they didn't do it with the 5770, and I don't expect that it was done with te 5870 either (but I'm not sure, as Apple's stock photos don't show the side we'd need to know for sure).

    But ATI does the card work (including the firmware), and has it made by another vendor (ATI's approach has been to allow thier cards to work in both PC's and Macs since the 3870 for sure, as they made a statement on this - it was even marketed specifically as "PC and Mac Edition").

    There's a couple of ways to get power (without over-drawing current off of the existing PSU or the PCB traces for the 6 pin connectors on the logic board):
    • Juice Box - Pro - clean installation; Cons - hard to find now, so it's expensive (newegg used to sell them cheap, but have discontinued it). eBay may be a potential source for better pricing.
    • Any PSU with sufficient power and connectors (jump the green and black wires to get the PSU to fire up). Pros - easy and cheap; Cons - ugly, as it hangs outside the system and needs to have the PSIG cables run inside the system.
  6. MacRoysan, Jun 17, 2011
    Last edited: Jun 17, 2011

    MacRoysan macrumors newbie

    Jul 22, 2010
    Ati 5870

    Yes you can run two (2) 5870 in a Mac Pro at the same time!

    Take a lock at this http://www.youtube.com/watch?v=lMiAgsr8m9M

    Best Regards,

    MacRoysan :apple:

  7. fouel macrumors member

    May 14, 2008
    I have tested the dual 5870 cards in my mac pro
    All of them are flashed card, not apple oem card.
    It did work.
    I think one apple 5870 and one flashing pc 5870 will work good.
  8. nanofrog macrumors G4

    May 6, 2008
    I'm not a fan of using the Y splitters off of the cables on the logic board, as it's possible to draw too much current off of the PSU rails and more importantly, the PCB traces that carry the power to the connectors on the logic board.

    There's an example in here somewhere that the HAL (Hot Air Leveling = solder coated copper traces) melted and shorted out = logic board had to be replaced. :eek: :(

    Given a logic board can run ~$800 USD or so, it's not worth it IMO, as a separate PSU is much cheaper (can be done for ~$100 or less).

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