Mac Pro Powers On/Off Repeatedly

Discussion in 'Mac Pro' started by slifermk, Nov 27, 2009.

  1. slifermk macrumors newbie

    Joined:
    Nov 27, 2009
    #1
    My Mac Pro has recently started having problems turning on. I'll press the start button, then it turns on for a couple of seconds, then turns off, then turns on again, then off, this goes on for maybe 5 or 10 minutes, then it starts up. I've reset the SMC using both methods in article HT1806, but that has no affect. My boot rom version is MP11.005C.B08. I downloaded the latest firmware 1.3, but when I tried to install it, I received a message that my computer did not require it. I did the extended hardware check using my Mac Pro install disk and it reported no hardware problems. This is the first problem I’ve had with my Mac Pro since I bought it 4 years ago. Does anyone know what the problem might be? Thanks.
     
  2. iamcheerful macrumors 6502

    iamcheerful

    Joined:
    Oct 3, 2008
    #2
    From a lay person's point of view, it appears to be the PSU.

    On a personal note ...
    I've experienced very similar on/off back then with a machine which was barely a year old, the tech narrowed it down to be a PSU issue. After a quick on-the-spot replacement (machine was and still is under on-site-warranty), I was back up running.
     
  3. nanofrog macrumors G4

    Joined:
    May 6, 2008
    #3
    A bad PSU is a strong possibility, but I have to ask: What about dust?

    It's possible it's gotten into the momentary switch (Power button), as well as everywhere else. It can cause major problems, such as over-heating.

    If this isn't the case, do you have Apple Care? As at that point you're going to have to take it in to an Apple store or get a PSU shipped to you.
     
  4. slifermk thread starter macrumors newbie

    Joined:
    Nov 27, 2009
    #4
    Thanks for the tips. I'll try blowing out the dust to see if that makes a difference. I'll also see if I can troubleshoot the PSU. Thanks again and I'll post the results.
     
  5. iamcheerful macrumors 6502

    iamcheerful

    Joined:
    Oct 3, 2008
    #5
    nanofrog's suggestion of dust is also a pretty high possibility. The machine is 4 years old and the dust accumulated would be quite substantial. The location where I reside now, is pretty much a dust magnet. If I take a day off from cleaning/maintaining the Mac Pro, dust starts to build up! I'm intending to do a major clean up of the interiors in Dec 2009. Going to have heck of blowing to do. Externally, it looks good to go, but once you inspect the inside ... :eek:
     
  6. nanofrog macrumors G4

    Joined:
    May 6, 2008
    #6
    You have a bench, or just a DMM?
     
  7. emt377 macrumors member

    Joined:
    Oct 12, 2008
    #7
    It's almost certainly thermal. First check the PSU voltages, but it probably needs to be cooled to reproduce. Wrap it in an ice pack for instance. If the PSU looks good use freezing spray on any regulators and switching caps you can find. Try swapping the video card. Finally if you haven't found the culprit by now pull drives one by one to see if the problem goes away.
     
  8. slifermk thread starter macrumors newbie

    Joined:
    Nov 27, 2009

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