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Thread: Mac Pro (Early 2008) Powers Up for Two Seconds Only

  1. #1
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    Default Mac Pro (Early 2008) Powers Up for Two Seconds Only

    Upon attempting to power up the the Mac Pro (Early 2008), the power button lights and all the right fans and noises whir, but only for maybe two seconds. Then, it dies. A few weeks ago, it would run to blue screen before dying, so I managed to get it to respond to the USB keyboard to open the DVD drive, allowing it to start from the DiskWarrior DVD. DiskWarrior seemed to fix it, until yesterday. Suspecting a bad power supply, I tried plugging directly into the wall, but with the same result. (But, that was a few weeks ago, so I'll try that again.)

    Is there a trick for opening the DVD drive in the two seconds available? The keyboard does not respond quickly enough. Maybe this is a problem in hardware, not software, anyway?

    Any ideas what horrors may have struck my beloved, if lonely Mac? I'm guessing hardware, because it's not asking to boot from one of the other disks with operating systems. On the default disk, the Mac is running... uh-oh; I'm supposed to know this... the highest version of Mac OS X that still includes Rosetta. Was that Leopard, or Snow Leopard? Another disk has Lion.

    Can't believe it's been three-and-a-half years since I last visited these forums. Worse, I've hardly touched my MacPro in that time. It has seen consistent but only occasional use. What a crime! TZ, UncleMac, other names I'll remember soon, you still out there? I had forgotten my username, but I remembered some posts, so I searched for them, recognized myself, updated my password, and here I am again. Amazing how strong the memories are of these forums.
    Last edited by Bozocity; 08-16-2012 at 05:33 PM. Reason: Clarity and omissions.

  2. #2
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    Default Update: Power Supply

    I tried once again plugging the Mac directly into the wall, bypassing the power supply. Started immediately, and booted normally. To confirm that this was the problem, I then shut down, and moved the power cord back to the power supply. Again, booted normally! So, whatever is happening is intermittent. Could still be an intermittent problem with the power supply, or does it sound like something else?

    The power supply is one of the big APCs made for hungry towers, but it is old. Is it typical for them to behave inconsistently while dying?

  3. #3
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    Any UPS can behave in almost any fashion when the batteries start getting some age.
    molṑn labe'
    "I am a mortal enemy to arbitrary government and unlimited power. I am naturally very jealous for the rights and liberties of my country, and the least encroachment of those invaluable privileges is apt to make my blood boil."
--Ben Franklin

  4. #4
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    Welcome back.


    Mostly UPSes behave when the batteries are shot.......but have seen a few do strange and bad things, up to shutting off machines. So much for "uninterruptible".

    I would run it from the wall for a while and see if the issue ever comes back.
    "Imagine if every Thursday your shoes exploded if you tied them the usual way. This happens to us all the time with computers, and nobody thinks of complaining." -- Jef Raskin

  5. #5
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    Default My UPS quirk ...

    I've had a issue over the past year or two about once a month or every other month...

    When I press the "power on" button to my iMac I get nothing. Pressing the power again in anyway does nothing. I usually am not paying enough attention to hear the CD/DVD make noise. So then I'll plug it into the wall it boots up fine. So I shutdown, plug into the UPS "chime" boots up fine. So I forget about it for a few months - until it happens again.

    My UPS is 5 plus years old. APC 800. I've yet to figure if it's the iMac, UPS or me.

  6. #6
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    Default

    Thanks for everyone's help. I'm going to get a new UPS. My favorite electrical supply house in the Big City:

    http://www.youdoitelectronics.com/

    recommends Tripp-Lite UPSes, because they take standard batteries that are easily and inexpensively replaced. Does that matter? By the time the battery is dead, is the UPS's ability to absorb spikes so reduced that it's better to replace it?

  7. #7
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    Quote Originally Posted by Bozocity View Post
    ... is the UPS's ability to absorb spikes so reduced that it's better to replace it?
    There's an interesting ? Does a UPS lose its ability to absorb spikes (assuming it receives none) simply due to time/age?

    and yeah I don't have an answer but I am interested to know the answer
    Damien,

  8. #8
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    Default Effects of Years of Small Surges

    "There's an interesting ? Does a UPS lose its ability to absorb spikes (assuming it receives none) simply due to time/age?"

    That's not what I meant to ask. Presumably, a UPS deadens many small surges over time. Collectively, do these degrade the remaining ability to absorb a catastrophic spike?

  9. #9
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    I think the short answer is NO......but just a hunch.

    I think generally figure a UPS battery will last about 3 years (run time always slowly shrinking), so yeah, good to be able to replace the battery. At least once.

    Have seen a few get less than 3 years, so pay attention to the warranty on unit and the battery too.
    "Imagine if every Thursday your shoes exploded if you tied them the usual way. This happens to us all the time with computers, and nobody thinks of complaining." -- Jef Raskin

  10. #10
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    My understanding (correct me if I am wrong) is that the step-down transformer out on the utility pole is designed to handle and catastrophic spikes by either dissipating the spike or exploding but is not suppose to let anything big get to your house. Also that if lightning strikes between your house and the pole and actually gets in your house you have more to worry about than the UPS… like your house burning down.

    Everybody's power quality varies though so regular (smaller) spikes may be common in some areas and not in others.
    Damien,

  11. #11
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    Interesting... Still, I once had a nearby strike of lightning, with blue flames leaping out of the outlets on the walls. Trashed a power supply, but the computers and house were unharmed. So, no harm to have good lightning protection!

  12. #12
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    YIKES! Yes no harm at all in having lightning protection..
    Damien,

  13. #13
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    Default It's the Computer, Not the Power Supply

    As the issue has worsened, I've discovered it's not the power supply, but the computer itself. The computer now will not boot even when plugged directly in the wall. I read an incomprehensible post on Apple's help forums about a known problem with Early 2008 MacPros being unable to boot. Apparently, there are some things I could try myself that might fix the computer, such as pushing buttons on the mother board. If they don't work, then the fix would require replacing failed hardware. Is anyone familiar with this problem, and able to help me understand what to try at home before bringing the Mac to the repair shop?

  14. #14
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    There is a PMU reset button on the Logic Board. No harm in trying it.

    Many G5s have the issue of being really solid for about the first 4-5 years or so, and then dying various deaths for no particular reason. Have seen many that need either a logic board or CPU replacement. Very hard to diagnose which, and neither is cost effective. Cheaper to buy another used G5 than parts. Better to move to a newer Mac.

    Wish I could give better news, but that's the way it is with G5s. I'm really glad Apple switched to Intel. Not perfect, but based on the G5 complexity, I think they were some of the most finicky, and least long-lasting Macs....so it is a bit scary to think what a G6 might have been.

    It could be that some model years are better or worse than others. I have been lumping all G5s into one group, except the liquid cooled (has its own special challenges).
    "Imagine if every Thursday your shoes exploded if you tied them the usual way. This happens to us all the time with computers, and nobody thinks of complaining." -- Jef Raskin

  15. #15
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    Default It's Intel, Not G5

    The affected computer is not a G5. It's Intel, an Early 2008 MacPro. Same basic plan? Is there a power management reset button on the motherboard?

  16. #16
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    There is a procedure for resetting the System Management Controller on a MacPro. Find it on this article:
    http://support.apple.com/kb/HT3964
    molṑn labe'
    "I am a mortal enemy to arbitrary government and unlimited power. I am naturally very jealous for the rights and liberties of my country, and the least encroachment of those invaluable privileges is apt to make my blood boil."
--Ben Franklin

  17. #17
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    Quote Originally Posted by ricks View Post
    There is a procedure for resetting the System Management Controller on a MacPro. Find it on this article:
    http://support.apple.com/kb/HT3964
    This procedure works if I follow it prior to every start. After shutting down, the power button is unresponsive until after I reset the System Management Controller.

  18. #18
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    Sounds like a dead battery on the motherboard.

    R
    molṑn labe'
    "I am a mortal enemy to arbitrary government and unlimited power. I am naturally very jealous for the rights and liberties of my country, and the least encroachment of those invaluable privileges is apt to make my blood boil."
--Ben Franklin

  19. #19
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    Default User Replaceable?

    Quote Originally Posted by ricks View Post
    Sounds like a dead battery on the motherboard.
    Something I can replace? or is it soldered to the board?

  20. #20
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    Is replaceable. Not worked on that model, I think it is behind the graphics card.

    Rick
    molṑn labe'
    "I am a mortal enemy to arbitrary government and unlimited power. I am naturally very jealous for the rights and liberties of my country, and the least encroachment of those invaluable privileges is apt to make my blood boil."
--Ben Franklin

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