Mac Pro 5.1 randomly resetting, red light on motherboard

Discussion in 'Mac Pro' started by silvertonesx24, Mar 29, 2016.

  1. silvertonesx24 macrumors newbie

    Joined:
    Dec 23, 2008
    #1
    Over the past few weeks, our Mac Pro 5.1 (12 core version) has been randomly resetting, as if someone pulled out the power and then plugged it back in. There seems to no consistency in terms of what is going on at the time, other than it is at the point now where it can't even reach the Login screen before randomly resetting. Essentially the machine is useless.

    The only clue is this red light shining brightly underneath the first hard drive bay.

    Any ideas? I have reset the PRAM, and reset the SMC (unplugged the computer for 15 min)

    [​IMG]
     
  2. saulinpa macrumors 6502

    Joined:
    Jun 15, 2008
    #2
    Which LED? Looks like it might the the over temp CPU B?

    Screen Shot 2016-03-29 at 1.14.43 PM.png
     
  3. silvertonesx24 thread starter macrumors newbie

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    Dec 23, 2008
    #3
    It looks like it is both OVTMP CPU A and OVTMP CPU B

    I unplugged the machine for several hours and now currently have it up and running, but who knows for how long. I did install a stat program to check temos. Are any of my results out of order?

    [​IMG]
     
  4. Lucas Godfrey macrumors 6502

    Lucas Godfrey

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  5. saulinpa macrumors 6502

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    Jun 15, 2008
    #5
    Looks a bit warm for idle. Pull the CPU board and blow some air through the heat sinks.
     
  6. silvertonesx24 thread starter macrumors newbie

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    Dec 23, 2008
    #6
    OK will do. The machine ended up shutting down about 10 min after taking that screenshot. Will try again tomorrow after unplugging it overnight.
     
  7. pastrychef macrumors 601

    pastrychef

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    New York City, NY
    #7
    Those temps look fine. They are much lower than what I see on mine.

    Screen Shot 2016-03-29 at 7.00.20 PM.png

    I like Fahrenheit. I have difficulty visualizing celsius temps.
     
  8. h9826790 macrumors 604

    h9826790

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    #8
    Run stress test and keep monitor the temperature. Poor cooling may be OK on idle, especially if your OAT is low. But will rise quickly under stress.

    If cooling system is the problem, you will know it in less than a minute.

    Otherwise, it should not be the temperature's problem.
     
  9. Lucas Godfrey macrumors 6502

    Lucas Godfrey

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    #9
    While thats nice, only the US, Guam and Belize use Fahrenheit for weather, and never when referring to computers.

    Fahrenheit literally means nothing to me or likely most people reading this, otherwise I could help.
     
  10. pastrychef macrumors 601

    pastrychef

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    #10
    The same goes for me, I couldn't help if it were in celsius.
    --- Post Merged, Mar 30, 2016 ---
    If the light is lit up at 97F and it shuts down after 10 minutes, there's something else wrong. Your CPUs are obviously not overheating.

    I don't see any benefit to trying to stress the CPUs and don't see how that's going to be even possible if the thing shuts down after 10 minutes at 97F. I suspect the CPU board or main logic board.
     
  11. silvertonesx24 thread starter macrumors newbie

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    Dec 23, 2008
    #11
    Started after being off and unplugged for 16h. Managed to get a quick shot of temps before it shut off 5 min later
    --- Post Merged, Mar 30, 2016 ---
    [​IMG]
    --- Post Merged, Mar 30, 2016 ---
    How could I diagnose a possible PSU issue?
     
  12. pastrychef macrumors 601

    pastrychef

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    #12
    I don't know of any way other than trial and error with a known good one.
     
  13. h9826790 macrumors 604

    h9826790

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    #13
    Do you have a PC GPU? The PCIe fan and PSU fan speed is not right, nothing too wrong, but they are not at normal idle speed.

    I am not sure if a problematic GPU can shutdown the Mac (especially when the GPU is not under stress).
     
  14. silvertonesx24 thread starter macrumors newbie

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    Dec 23, 2008
    #14
    Yes I do. GTX960 with Nvidia Web Drivers.
     
  15. h9826790 macrumors 604

    h9826790

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    #15
    Is your RAM ECC?

    Do you have the original GPU? Can you put that back in for testing purpose?
     
  16. ActionableMango macrumors 604

    ActionableMango

    Joined:
    Sep 21, 2010
    #16
    When it turns off, can you immediately turn it back on again?

    The service manual has detailed diagnosis steps starting on page 37 for "Intermittent Shutdown" problems.

    Symptoms:
    "Computer intermittently shuts down, restarts, sleeps"

    If I were you, I'd Google for the service manual, obtain a copy, and go through that procedure.

    Unfortunately intermittent problems are inherently difficult to diagnose. If the system is working at the moment you perform a test, then the test will pass.
     
  17. pastrychef macrumors 601

    pastrychef

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    #17
    The only time I have ever heard of a video card causing a Mac Pro to shut down is when it is drawing too much power. Based n the screenshots provided, there doesn't seem to be much load on the video card at all.
     
  18. MacOvation macrumors newbie

    MacOvation

    Joined:
    Jul 21, 2008
    #18
    Greetings
    Just a thought, but, this inconsistent and variable activity might be related to PRAM so I'd check the voltage of the PRAM battery and replace it if low. Good luck.
    Patrick
     

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