Motherboard + processor compatability

Discussion in 'Mac Pro' started by David____, Feb 12, 2016.

  1. David____ macrumors newbie

    Joined:
    Feb 12, 2016
    #1
    Based on tests I've run, I think I have a bad motherboard and a bad video card.* The Mac Pro is a A1186 model. My motherboard is a 820-2129-A with 3.0GHz CPUs, however I can't find them for sale on eBay. I can find a very similar one, the 820-1976-A for dirt cheap on eBay though. The big question is, will this older mb, meant for 2.66GHz processors, which looks almost identical to mine, be compatible with my 3.0Ghz processors?

    I saw the mb + CPU compatibility list, but for some reason it doesn't list the motherboard in the table. Instead it just states general models like "Mac Pro 5.1". I may be wrong but that seems way too vague. The Mac Pro 5.1 probably had 5 different motherbaords that it could have come with, each with different compatible CPUs. If that is true, it would seem that the table is not useful to me.


    *When turned on, motherboard diagnostic LEDs only have "EFI GD" and "TRICKLE" lit up. The video card has both red LEDS on indicating overtemp and bad power. Video card heatsink was clogged with dust so the video card is likely bad. Power supply was replaced without any improvement. A working NVIDIA gfx card was put in instead with no improvement.
     
  2. MacVidCards Suspended

    Joined:
    Nov 17, 2008
    Location:
    Hollywood, CA
    #2
    #1, nobody with a Mac calls them "Motherboards"

    They are "Logicboards", you can't expect PC world stuff to translate exactly. The days of the "MoBo" are past.

    Take some time to do some reading. In reality, very few Logicboard versions.

    For 4,1 and later, the CPUs don't connect directly to the logicboard, and have nothing to do with it. As you will discover with some research.
     
  3. h9826790 macrumors 604

    h9826790

    Joined:
    Apr 3, 2014
    Location:
    Hong Kong
    #3
    In fact, use "Mac Pro 5,1" in the table is much better than use the part number. No matter how many variations are there. As long as the firmware is 5,1, those CPU will be supported. On the other hand, a logic board with exactly the same part number, but with 4,1 firmware, some CPU will not be supported. So, the part number is actually meaningless.
     
  4. David____ thread starter macrumors newbie

    Joined:
    Feb 12, 2016
    #4
    I don't know how I will find the firmware version on a machine that doesn't boot. What would be the next step in finding out, for sure, whether or not the logicboard in question will be able to replace my original logicboard?
     
  5. h9826790 macrumors 604

    h9826790

    Joined:
    Apr 3, 2014
    Location:
    Hong Kong
    #5
    A quick search shows that the A1186 should be a 1,1, but can be flashed to 2,1.
     
  6. scott.n macrumors 6502

    Joined:
    Dec 17, 2010
    #6
    "A1186" : Mac Pro 2006 -2008 (1,1 - 3,1)
    "A1289" : Mac Pro 2009 - 2012 (4,1 - 5,1)

    The OP's 820-2129-A logic board is part number 661-4307 from the Mac Pro 2,1.

    The 820-1976-A logic board found on eBay is part number 661-3919 from the Mac Pro 1,1.

    I know that if you had a 1,1 machine with the latter board, you could drop in your dual 3.0GHz CPUs (X5365) without difficulty, so the board/CPUs are definitely compatible. What I don't know is if the older board can physically be installed in the 2,1 - if all mounting posts line up, if the PSU/memory risers/heat sink/etc all are compatible, and so on. Maybe someone who's more knowledgeable about the 1,1 and 2,1 can respond.
     
  7. ActionableMango macrumors 604

    ActionableMango

    Joined:
    Sep 21, 2010
    #7
    Probably hundreds or thousands of people have upgraded processors in their Mac Pros and not once have I ever seen someone say that they also change out their logic board in order for their faster processors to work. I've also done so twice myself.

    If you are still concerned, then buy one from a place with a return policy.
     

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