Mac pro 5,1 power issue

Discussion in 'Mac Pro' started by mostafiz28, Dec 5, 2016.

  1. mostafiz28 macrumors member

    Feb 16, 2013

    My 2012 mac pro is showing power issues. when I press the power button, I can hear the regular click, the LED lights up but after a few seconds, I hear another click and the machine goes off then attempts to restart again but gets into a loop of restarting until I pull the power plug off. Sometimes after a few attempts it will boot up and run for a few minutes and then get into the same restart loop. Then sometimes after a few attempts the instead of booting, the fans will start to spin at full spin before powering down automatically. I have tried resetting PRAM, SMC, replaced the GPU, tried with the RAM that came with the machine but nothing changed a thing. Is this likely to be a power issue, or a logic board failure. Thanks for your help in advance.
  2. ActionableMango macrumors G3


    Sep 21, 2010
    My guess is bad power supply but it could be a lot of things. Are any of the internal diagnostic LEDs lit?
  3. mostafiz28 thread starter macrumors member

    Feb 16, 2013
    No, none of the LEDs are lit. If I press the diag. button, the amber one is lit and if the machine manages to boot up, a couple of green ones are lit.
  4. jennymc, Aug 12, 2017
    Last edited: Aug 13, 2017

    jennymc macrumors newbie


    Dec 28, 2011

    I have Mac pro mid 2010, 5,1 quad code model. It was working fine since 2010. few days back there was red light near CPU heatsink, but it disappeared when cleaned all dust and it start working again. Next morning when I switched on again, it's dead, no light, no sound, no fan movement, nothing is happening.
    • When connecting the Mac Pro to AC power, the LEDs for OVTMP CPUA and OVTMP CPUB briefly flashes red and also momentarily flash red immediately after the Mac Pro is disconnected from AC power ( note 1 & note 2, page no. 34 )
    • after pressing DIAG LED button on board, the 5V STBY LED illuminates
    This indicates the Power supply and Logic board is fine. The power button was giving problem from last 1-2 months, I need to press sometime 2-3 time to start the system.

    I have tried to jump the SYS PWR pads to start the mac pro as (shown in the video, possibly on correct power-on pads), but no result. Can someone please suggest what is the best solution or what might be the main cause?

    here is the video link

  5. Synchro3 macrumors 68000


    Jan 12, 2014
  6. jennymc macrumors newbie


    Dec 28, 2011
    the issue regarding the red light near the CPU heatsink (cpu logic board) was solved after cleaning dust. The main issue is near DIAG LED button, on the backpanel / main logic board
  7. Sebct macrumors regular

    Dec 18, 2010
    London, UK.
    Did you have any luck getting your machine to boot?

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