How could I power 2 GFX cards in my Mac Pro (First Gen)

Discussion in 'Mac Pro' started by xenova, Feb 27, 2010.

  1. xenova macrumors newbie

    Joined:
    Feb 27, 2010
    #1
    Hi guys, my first post here and hopefully posted in the right place! :)

    I'm currently working on completely migrating from my PC to my Mac (having kvm switches here and there has got very tiresome and I'm now very much restricted for room.) So I've set up boot camp and I am able to dual boot between OS X and Windows 7. I have two graphics cards currently sat inside the Mac, 1 ATI 4870 which I use with Snow Leopard, and a GTX 280 (which I've pulled from its water cooled environment in my PC) to use in Windows.

    Now the problem, I use OS X exclusively for productivity apps like FCS3 and Adobe CS4, and wish to use Windows preliminary for recreation and games, which is where my GTX280 comes in.

    Currently I have both cards in the machine, naturally OSX doesn't detect the 280, and I am fine with that. In windows I am able to utilize both cards, Windows detects both cards, installs drivers for them and works no problem running games on either card (preferably the 280 as it's relatively more powerful)

    But that's with the aid of an additional PSU to separately power the 280 as the 4870 uses up both of the 6-pin PCI-e sockets on the Mac Pro Logic Board.

    My real question is, am I able to buy two 4-pin molex y-splitters (still allowing the power to the DVD ROM drives), and then using the spurs to connect those to a '4-pin molex to 6pin PCI-e connector'; with addition to getting two 6-pin PCI-e Y splitters and connecting the 2 spurs to both the 4870 and the 280 via 6 to 8 pin PCI-e connector? -- Yeah the 280 is a power hugry card! :rolleyes:

    I've contemplated this myself knowing that the Mac Pro as a rated 1KW PSU, what concerns me is the PSU rails. Even if I can get these connectors to wire up the 280 with the built-in PSU, I don't know if the PSU's rail's will be able to provide the current required.

    Any ideas you guys could give me would be greatly appreciated! :confused:

    Apologies for the epic post :p
     
  2. Cindori macrumors 68040

    Cindori

    Joined:
    Jan 17, 2008
    Location:
    Sweden
  3. xenova thread starter macrumors newbie

    Joined:
    Feb 27, 2010
    #3
    Good info however, it doesn't detail how to power a card which has a 6-pin and an 8-pin PCI-e power connector. I wouldn't have too much of a problem if thw GTX280 was powered with two standard 6-Pin connectors like the 4870.

    I guess I'm going to have to make my own power connectors for this job. If only Apple were easy about these things.

    Next thing to do is get a schematic of the wire out of the PSU and see if can find alternative points to power this card.
     
  4. Cindori macrumors 68040

    Cindori

    Joined:
    Jan 17, 2008
    Location:
    Sweden
    #4
    you can plug a 6pin into a 8pin hole without power issues.

    ther are adapters to buy also if you'd like that.
     
  5. xenova thread starter macrumors newbie

    Joined:
    Feb 27, 2010
    #5
    I tried that, however the 280 will not power up using 2 6-pin connectors, it requires the additional 2 -12v connectors on the 8-pin block. I just get a red LED on the back of the card.
     
  6. Cindori macrumors 68040

    Cindori

    Joined:
    Jan 17, 2008
    Location:
    Sweden

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