4 pin Molex to 8 pin PCI

Discussion in 'Mac Pro' started by DawgBone, Apr 20, 2013.

  1. DawgBone macrumors newbie

    Jan 17, 2013
    I'm interested in an ASUS NVIDIA GeForce GTX 570 for my 3.1 MP. It needs one 6 pin and one 8 pin power connection.

    I was thinking about using the Molex connection for the 2nd optical drive and found these converter cables:

    4 pin Molex to 6 pin PCI:

    6 pin PCI to 8 pin PCI:

    I wasn't able to find a 4 pin Molex to 8 pin PCI.

    Has anyone tried this before? How did it work for you? Thanks.
  2. handheldgames macrumors 6502a


    Apr 4, 2009
    Wrong connector. I haven't found anyone anufacturing a cable with the proper connector. You could modify a standard Mac Pro pci-e power cable for the task. I have a post in this forum detailing the specifics.

  3. bax2003 macrumors 6502a


    Dec 25, 2011
    Belgrade, Serbia
    Tried on my ex MP 3.1. ASUS GTX570 Direct CU II (6pin + 8pin), with two standard Mac Pro 6 pin PCIe booster cables and one of them converted to 8 pin with adapter like that. Everything was fine.
  4. DawgBone thread starter macrumors newbie

    Jan 17, 2013
    Thanks, Bax.


    I'll check it out. Thanks.
  5. DawgBone, Apr 21, 2013
    Last edited: Apr 22, 2013

    DawgBone thread starter macrumors newbie

    Jan 17, 2013
    My revised strategy is to use a 4 pin Molex to 6 pin PCIe adapter to tap into the ODD Molex connector:


    Then use a 2 x 6 pin to 8 pin "Y" adapter to connect with the video card:


    One of the 6 pin sources for the "Y" adapter will come from the motherboard using this:


    The other will come from the Molex adapter.

    HandHeld's approach is more elegant, since you would not have to thread a cable from the ODD compartment:


    But I really don't want to fabricate my own cable. Does anyone see any problems with this? Thanks.
  6. handheldgames macrumors 6502a


    Apr 4, 2009
    The connector you are showing is the wrong size. Thats a P4 ATX power connector... Just a bit TOO big for a fit. I have extras here if you need any :p You will be pleasantly surprised to find out that the MacPro connector is a (going from memory here) mini-fit jr molex 4 pin dual row hanging connector:


    Hope this helps. I don't want to make my own cables either, I just may once I get past this crazy programming deadline.

  7. DawgBone, Apr 22, 2013
    Last edited: Apr 22, 2013

    DawgBone thread starter macrumors newbie

    Jan 17, 2013
    Thanks for the reply, HandHeld. I'm clearly missing something here. I'm a hacker, but my ignorance of hardware is truly breathtaking.

    This is the ODD connector I was planning on tapping:


    Isn't that a 4 pin Molex? Or maybe you mean one of the other cables? My Mac is an early 2008 3.1.

    Thanks for your help.
  8. DawgBone, Apr 24, 2013
    Last edited: Apr 24, 2013

    DawgBone thread starter macrumors newbie

    Jan 17, 2013
    Well, I've decided to not tap additional power from the motherboard after all.

    Instead I plan on adding a supplemental power supply in the ODD compartment similar to what Dr. Stealth describes here:


    I will probably be installing two GTX 570s or 580s instead of the 680s the Doctor used. They will be used for programming work in CUDA and OpenCL rather than gaming.

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