Mac Pro 2013 acting strange

Discussion in 'Mac Pro' started by Draeconis, Oct 20, 2015.

  1. Draeconis macrumors 6502a

    Joined:
    May 6, 2008
    #1
    Hi all,

    My colleagues Mac Pro Late 2013 is acting really odd. When you start it, it passes POST and you see the Apple logo and the loading bar (running 10.10.5) as you'd expect. It gets to about 1/3, then the screen glitches, the fan starts to run at about 80%, and the machine then puts itself to sleep. The screens seem to turn on and off sporadically, as if receiving a signal briefly, then not. The machine also responds to ping, but erratically, sometimes 0.2ms, sometimes around 30ms, or even up to 150ms or so.

    • We've tried resetting the SMC, no difference.
    • When we try to reset the NVRAM, instead of restarting the machine turns off.
    • Running fsck -fy from single-user mode yields nothing.
    • Booting from an alternative source (USB, NetBoot, Internet Recovery) makes no difference.
    • AHT via Internet Recovery finds no issues.
    • Visual inspection of the components doesn't reveal anything glaringly obvious that might have failed.

    It's a bizarre one. I've never seen a machine act like this. Anyone have any ideas? I have a suspicion it might be a GPU issue, but I'm at a loss why the machine puts itself to sleep straight away.
     
  2. MacUser2525 macrumors 68000

    MacUser2525

    Joined:
    Mar 17, 2007
    Location:
    Canada
    #2
    Use the command + v keys at the same time when booting to get a verbose (text) boot then you will see where it fails in the messages that scroll by.
     
  3. Draeconis thread starter macrumors 6502a

    Joined:
    May 6, 2008
    #3
    We seem to have fixed it by reseating all the RAM. I still can't explain what it was doing though.
     
  4. MacUser2525 macrumors 68000

    MacUser2525

    Joined:
    Mar 17, 2007
    Location:
    Canada
    #4
    How would you never having seen where it died off, gotta love computers and all the mysterious things they do....
     
  5. Draeconis thread starter macrumors 6502a

    Joined:
    May 6, 2008
    #5
    This issue has returned.

    We've methodically removed all RAM, and tried the following;
    • One DIMM in Slot 1 - Mac boots but hangs before reaching the login window. Fan spins to around 50%
    • Same DIMM in Slot 2 - Mac boots, but we never see the Apple logo, machine than automatically enters Sleep without any keyboard command or button pressed to tell it to do that.
    • Tried this same DIMM on it's own in an different identical Mac Pro, and it boots fine.
    Is it reasonable to assume therefore that the issue lies with the Mac Pro itself?
     
  6. MacUser2525 macrumors 68000

    MacUser2525

    Joined:
    Mar 17, 2007
    Location:
    Canada
    #6
    Yes I would think so and it is time as well to either get the diagnostic disk or take it to a store to get it checked by Apple.
     
  7. Draeconis thread starter macrumors 6502a

    Joined:
    May 6, 2008
    #7
    AHT comes back fine, tried this one before. :/

    We send stuff off to Amsys, but knowing them the machine could come back in worse condition than it left in.
     

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