Mac pro and probably a PSU problem

Discussion in 'Mac Pro' started by srfval, Nov 6, 2011.

  1. srfval macrumors newbie

    Jul 30, 2008
    Hi all,
    I have a July 2008 mac pro which seems to have a problem with the Psu.
    When i press the power button it starts and after some seconds before it logs into OS it shuts down.
    Sometimes it starts successfully and it might work without problems or it might shutdown during operation.
    As i read to some forums many owners of the 2008 model experience such problem and those who changed the PSU solved the problem.

    Now, because of the days apple wants to keep my Mac for checking is forbitten for my work, I want to change the PSU myself.
    So, which is the PSU i have to purchase in order to be compatible? Does it have a specific number i must check before purchasing a new one?
    Any details or suggestions are welcome!!!

  2. srfval thread starter macrumors newbie

    Jul 30, 2008
  3. srfval, Nov 7, 2011
    Last edited: Nov 8, 2011

    srfval thread starter macrumors newbie

    Jul 30, 2008
    Yes, i found that too...
    Do you have any suggestions regarding my mac's problem?
    Think its a PSU issue?

    PS: Is it hard to change it myself?

  4. 666sheep macrumors 68040


    Dec 7, 2009
    It's quite easy to replace PSU. See service manual for 2008 on Scribd.
    Symptoms you experience are pointing on PSU, but you can be but 100% sure only when you'll replace it with new/tested one.
  5. imacdaddy macrumors 6502a

    Feb 2, 2006
    I'm getting my PSU replaced on my 3,1 MP (early 2008). I had lots of problems after upgrading to Lion. But I had no way of proving that it was Lion's fault for the shutdowns and fans in overdrive.

    Apple just replaced my motherboard and upon pickup, I'd asked for them to power on the system. It didn't boot up. Maybe because of the configuration of my MP (4 x HDD and HD 5870). They said something is wrong with the PSU and couldn't drive the system. But they were able to power up using a different video card.

    Did you encounter this problem after installing Lion?
  6. srfval thread starter macrumors newbie

    Jul 30, 2008
    I finally received my new PSU yesterday and replaced it immediately.
    Last attempts with the old PSU were unsuccessful. It shutdown seconds after power on.

    I replaced it and it seems to be working great. No problems for the last 8 straight working hours. So, it seems the problem was the PSU.

    Now, unfortunately I still have the Snow Leopard, so I cannot help you with Lion. But, if you had the same symptoms as mine, 99,9% its the PSU.
    I read somewhere that when the MacPro is booting it checks if the PSU outputs the correct voltage from each cable.
    If it finds an error it shuts down.

    That must have been my problem.

    Hope you find a solution soon.

    Thank you all!

    PS: I do not think its your configuration the problem. I too have 4 internal HDDs (but the Nvidia VGA), 2 external and sometimes 3, an external DVD Recorder, a wacom tablet, and sometime I connect via firewire my camera for grabbing. All at the same time and its working great.

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