Need help with using 2 GPU's in Mac Pro 2009

Discussion in 'Mac Pro' started by MentalVizion, Oct 24, 2014.

  1. MentalVizion macrumors regular


    Oct 30, 2013

    I am currently trying to use Unreal Engine 4 with just a 5770 (Mac Edition) installed. As expected, I get quite the low performance.

    Since the GTX 680 and the Radeon HD 7950 are out of my budget, I thought I'd take the "windows card" route instead.

    I read the stickied thread regarding non EFI graphics cards and would have come to the following conclusion/questions:

    Can I use a "official Mac card" in PCIe Slot 1, and a regular non EFI one in slot #2, and still have my boot screen?

    If so, can I connect a total of however much displays are supported on both of these cards?

    Do I get the full power of both cards? How does OS X know which one I'd like to use for certain tasks? Is this all done automatically between both GPUs?

    I read, the Mac Pro 2009 motherboard only supports up to 225W of power consumption, thus meaning, if I would continue using the 5770, the other card should not exceed a TDP of 117W? (108W (5770) + 117W (GPU#2) = 225W)

    I hope some of you can bring some light to the end of this dark tunnel :D
  2. superdx macrumors regular

    Jul 23, 2009
    You can use your original 5770 card in conjunction with a "windows" graphics card. The boot screen would only show up on the monitors connected to the 5770 though.

    There really is no other benefit to an EFI card. Drivers are more important.

    You can connect as many screens as you have connectors on both cards. I have done the same on my Mac and have 5 displays connected.

    If the card you are adding requires additional power, you can use the connectors on the Mac Pro motherboard. But if the new card is power hungry, you need to use an external power supply.

    GTX 680 (Windows version) works fine on a Mac Pro, just make sure it has 2x6pin connectors. It draws power from special connectors on the motherboard, which are then converted to 6pin. You can find the power cables for Mac Pro from anywhere.

    Example here:

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