Mac Pro 3,1 Losing Power?

Discussion in 'Mac Pro' started by bwillwall, Aug 7, 2015.

  1. bwillwall macrumors 6502a

    bwillwall

    Joined:
    Dec 24, 2009
    #1
    I've been struggling off and on with this Mac Pro for several days. It worked flawlessly until suddenly it started shutting off at random times. It had a dead PRAM battery, so then I replaced it and it worked perfectly for days, that is until I installed new RAM and a new GPU and the problem started again. It's like being messed with did something to it? Maybe unplugging the power supply caused it to lose some of its charge?

    What happens is this, it works fine until suddenly theres a click sound and it immediately loses power. Again, it worked for days, and then other times it only worked for minutes or an hour or so.
     
  2. VAGDesign macrumors 6502

    VAGDesign

    Joined:
    Feb 1, 2014
    Location:
    Greece
    #2
    Backup your data and replace the hard drive you have your OS. It's not anything else, it's the drive that failing.
     
  3. netkas macrumors 65816

    Joined:
    Oct 2, 2007
    #3
  4. bwillwall thread starter macrumors 6502a

    bwillwall

    Joined:
    Dec 24, 2009
    #4
    And what makes you so sure of this?
     
  5. VAGDesign macrumors 6502

    VAGDesign

    Joined:
    Feb 1, 2014
    Location:
    Greece
    #5
    This:
     
  6. bwillwall thread starter macrumors 6502a

    bwillwall

    Joined:
    Dec 24, 2009
    #6
    Ah ok. Thanks I will test it out!
     
  7. haralds macrumors 6502

    haralds

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    Jan 3, 2014
    Location:
    Silicon Valley, CA
    #7
    Amen...
     
  8. bwillwall, Aug 8, 2015
    Last edited: Aug 8, 2015

    bwillwall thread starter macrumors 6502a

    bwillwall

    Joined:
    Dec 24, 2009
    #8
    Actually the click isn't coming from the HDD. I took it out and it makes that click sound when I shut it down manually still. It's either a normal sound coming from the PSU or motherboard or it has to do with something that's broken. Either way, it still fails when I boot from a USB drive without the hard drive installed.
     
  9. nigelbb macrumors 6502a

    Joined:
    Dec 22, 2012
    #9
    I suspect that the click is coming from a dodgy power supply.
     
  10. 1madman1 macrumors regular

    Joined:
    Oct 23, 2013
    Location:
    Richmond, BC, Canada
    #10
    The "click" is probably a relay. My 4,1 and 5,1 would shut off in a similar manner if I overloaded the PSU. If your system shuts off while doing something straining the new GPU you may need to find an alternate method to power it. Otherwise I suspect you may need a new power supply.
     
  11. VikNomad macrumors member

    Joined:
    Nov 13, 2009
    #11
    Can new video card be a culprit? If it has no power from extra connection and suddenly draws too much from PCIe lane?
    Maybe 6 pin power cable is a problem. Just my $0.02
     
  12. netkas macrumors 65816

    Joined:
    Oct 2, 2007
    #12
    Just read my post, even your phrase " I installed new RAM " hints at it, the more ram you install, the more it sucks power off psu, and ram fails first if psu doesn't provide enough volts on its output.
     
  13. bwillwall thread starter macrumors 6502a

    bwillwall

    Joined:
    Dec 24, 2009
    #13
    Okay but isn't it sort of dangerous to work inside a PSU? I don't really know what I'm doing with it. lol
     
  14. bwillwall thread starter macrumors 6502a

    bwillwall

    Joined:
    Dec 24, 2009
    #14
    Okay but isn't it sort of dangerous to work inside a PSU? I don't really know what I'm doing with it. lol
     
  15. netkas macrumors 65816

    Joined:
    Oct 2, 2007
    #15
    Check voltage from power supply and on vram first with some monitoring utility
     
  16. bwillwall thread starter macrumors 6502a

    bwillwall

    Joined:
    Dec 24, 2009
    #16
    OK guys I tried testing the PSU, me and somebody else decided it must have something to do with the power supply. I broke down and bought a 3,1 PSU (which isn't very cheap) that I can return in the case it does not fix my problem. I will let you know what happens.
     
  17. bwillwall thread starter macrumors 6502a

    bwillwall

    Joined:
    Dec 24, 2009
    #17
    Not PSU, I'm returning it because there was no difference.

    The resolution I found was actually resetting the PRAM. I had done this before, but somehow it had a problem again. There could be some sort of motherboard problem here but until this problem is reproducible I'm not spending any money on it as it's working great at the moment. If something changes I will post it.
     

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