Weird cpu failure

Discussion in 'Mac Pro' started by japerapaper, Oct 2, 2016.

  1. japerapaper, Oct 2, 2016
    Last edited: Oct 2, 2016

    japerapaper macrumors newbie

    Joined:
    Oct 2, 2016
    #1
    Hi guys, I'm hoping someone can point me in the right direction because im out of ideas.

    I wanted to upgrade my macpro 4.1 to 5.1 by swapping the cpu's to 2 x5680's.

    The upgrade went fine at first, but after 3 days it started freezing like 10 sec after boot.

    I swapped every piece of hardware in the mac with something else but it wouldnt help, so i went back to the CPU's. Removed CPU B from socket B and all is fine, no freezes. Placed CPU B in Socket A, all is fine no freezing. Putting back in both cpu's: Bam, freeze within 10 sec, the mac wont recover from the freeze.

    I thought it might be broken B socket so I just put back in the old CPU's, and all is fine.

    I'm out of idea's... anyone?
     
  2. ColdCase macrumors 68030

    Joined:
    Feb 10, 2008
    Location:
    NH
    #2
    Can the power supply or traces handle the additional CPU load of the two upgraded parts?
     
  3. japerapaper thread starter macrumors newbie

    Joined:
    Oct 2, 2016
    #3
    Standard is 980 Watt so that should be enough, stripped all the extra hardware and still the same problem..
     
  4. flowrider macrumors 601

    flowrider

    Joined:
    Nov 23, 2012
    #4
    Sure, my cMP 5,1 is loaded and running X5677s just fine. A lot of other members have upgraded with no issues. The OPs issue sounds like a bad CPU to me.

    Lou
     
  5. japerapaper thread starter macrumors newbie

    Joined:
    Oct 2, 2016
    #5
    The thing is, If I run it on 1 CPU it runs fine, same story for both cpu's. Is there anything that can be faulty in a CPU that only shows up if they have to work together with another one?
     
  6. h9826790 macrumors G4

    h9826790

    Joined:
    Apr 3, 2014
    Location:
    Hong Kong
    #6
    So, the symptoms is...
    1) When both X5680 installed, computer freeze.
    2) When only one X5680 installed, no matter which one, computer won't freeze.
    3) When both old CPU installed. computer won't freeze.

    Therefore...
    From 1, we can tell something is wrong when both X5680 is installed.
    From 2, we can tell both X5680 looks good individually.
    From 3, we can tell the CPU tray itself looks good.

    Hence...
    The biggest possibilities is that the X5680 can't talk properly with the other X5680.

    I only know very very little about CPU. Is this possible QPI link related? Or if the CPU connector is dirty /partial damage, and it only makes the connection between the X5680's become intermittent?
     
  7. flowrider macrumors 601

    flowrider

    Joined:
    Nov 23, 2012
    #7
    Guess, I misunderstood. Sorry! Check the markings on the new CPUs. Are they exactly the same? When it fails, are there any red lights on the logic board?

    Lou
     
  8. japerapaper, Oct 3, 2016
    Last edited: Oct 3, 2016

    japerapaper thread starter macrumors newbie

    Joined:
    Oct 2, 2016
    #8
    No problem! There isnt any code on the CPU's, they are delidded by someone else there mightve been something on the IHS.
    --- Post Merged, Oct 3, 2016 ---
    All correct! Same for me, also QPI I know nothing about. No visual damage visible. Unfortunatly not an extra pair of 5680 lying around either.
     
  9. thornslack macrumors 6502

    Joined:
    Nov 16, 2013
    #9
    Have you checked your thermals? Is the one socket over heating?
     
  10. japerapaper thread starter macrumors newbie

    Joined:
    Oct 2, 2016
    #10
    Yes ive checked! And no there not..
     
  11. pastrychef macrumors 601

    pastrychef

    Joined:
    Sep 15, 2006
    Location:
    New York City, NY
    #11
    Are you sure the steppings of both CPUs were the same? Is it possible that you got engineering samples?
     
  12. japerapaper thread starter macrumors newbie

    Joined:
    Oct 2, 2016
    #12
    Oeh thats clever, but how would I check that! I think the coding was on the IHS, wich has been removed..
     
  13. pastrychef macrumors 601

    pastrychef

    Joined:
    Sep 15, 2006
    Location:
    New York City, NY
    #13
    If you have Windows installed, I think the app called CPU-Z will show stepping.

    kr5acl.png
     
  14. japerapaper thread starter macrumors newbie

    Joined:
    Oct 2, 2016
    #14
    I dont think thats the actual stepping, I remember it being a much longer hex string
     
  15. rshrugged macrumors 6502a

    Joined:
    Oct 11, 2015
    #15
    I'm not sure what you're referring to but through Mac, CLI you can get CPU info, including stepping, using this --
    Code:
    sysctl -a | grep machdep.cpu
     
  16. ITguy2016 Suspended

    Joined:
    May 25, 2016
    #16
    It's likely one of the CPUs is bad and thus resulting in the inability to use it in a dual CPU configuration. Is it possible to exchange them for a different pair?
     

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