Replace logic board on Mac Pro 2,1 (661-4307) with one from Mac Pro 3,1 (661-4449)

Discussion in 'Mac Pro' started by zaa, May 30, 2014.

  1. zaa macrumors newbie

    May 30, 2014
    Hi guys,

    I have been struggling to fix my Mac Pro 2,1 (8-core) Intel Xeon X5365 (Clovertown) processors (Early 2007) for many weeks now.

    I'm pretty sure that a logic board malfunctioning, but might be something else.
    Basically, when I press start up button, Mac turns on, fan on graphic card start spinning at full speed, start up chime and that's it. Black screens, graphic card fan spins at full speed, no any other sounds, no error chime, no light blinks, nothing. Could it be PSU issue?

    So, I'm planning now to replace logic board (661-4307) with one from Mac Pro 3,1 (661-4449) and keep the same CPUs and RAM? The reason is that I can not find the original board from 2,1. There are plenty 1,1 and 3,1 on sale and I think that 3,1 is a better option. I have read that 1,1 and 2,1 are compatible logic boards, but there is no information whether 3,1 is backwards compatible with 2,1 hardware and a box.

    Could you please advise if it is feasible to replace logic board as I described above? Would the logic board actually fit in? Is it possible to keep the same CPUs (Clovertown) and RAM (SMT 8 x 1GB PC2-5300 ECC DDR2-667)?

    Thank you!
  2. GP-SE macrumors 6502

    Feb 27, 2013
    2,1 and 1,1 are the same, just different firmware
    however you're issue sounds like a GPU issue, and not a logic board issue, I say this because if you hear the startup chime, most likely everything is good with the logic board, and your GPU is at fault.

    try a SMC Reset and Pram Zap, search askjeeves for instructions from apple
  3. zaa thread starter macrumors newbie

    May 30, 2014
    Thank you for the advice.

    Unfortunately it is not a GPU. The symptoms are exactly the same with a couple of other 100% working GPUs. I actually tried all possible resets, replaces of different parts (borrowed from a friend) and only two things remaining under suspicion Power Unit or logic board.

    What about 3,1 and 2,1 compatibility?
  4. reco2011 macrumors 6502a

    May 25, 2014
    I believe the 3,1 uses PC6400 memory so I'm not certain if your existing memory will work (as it's PC5300).
  5. kwarwick43 macrumors member

    Aug 11, 2008
    3.1 has a slightly different physical configuration for the RAM riser boards in that the top riser board is upside down. I don't have a 1,1 or 2,1 to compare, but I think you may need to also get the riser cage from the 3,1 in order to make this work.
  6. Lucas Godfrey macrumors 6502

    Lucas Godfrey

    Jul 12, 2010
    Somewhere between Here and There
    This guy is right but I don't recommend it at all, if you do decide to use a 3.1 board then you'll also need to get a 2008 memory cage, 2008 memory risers and also a new CPU cover (2006/7 have a different width cover to the 2008). It seems too much work for what could be done with a 1.1 board for much less cost/effort.


    The memory is compatable, a 2008 board will happily use 667mhz ram, but you'd need the 2008 riser cards, in my experience the original cards don't work in later models.

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