Mac Pro 3,1 Early 2008 - Need help diagnosing power problem

Discussion in 'Mac Pro' started by hualon, Sep 5, 2013.

  1. hualon macrumors 6502

    Feb 5, 2008
    I have an Early 2008 Mac Pro (3,1). I have 18GB ram and an ATI Radeon HD 5770 1024 card installed.

    I have made no hardware changes in over a year. I regularly shut down the computer nightly.

    The symptom: I push the power button on the front and I hear a single click from the power supply.

    I do not get boot, do not get chime, do not get fan spin, do not get video. Just *CLICK* and then nothing.

    Steps I have taken so far:
    1. Reset the SMC (unplugged for more than 15s, plug in, push power button)
    2. Tried a different power cable (yes, I really did)
    3. Tried a different outlet (yes but not a different _circuit_)
    4. Removed the RAM cards and, with power plugged in, pressed the diagnostic LED button. LED #2 (Standby Trickle Pwr) comes on solid yellow. According to the service manual this tells me that the PSU is providing trickle power

    I can give it a kind of jump start by removing the power cable, plugging it in, and pushing the power button really quick. I'm using the computer right now, in fact.

    After doing the jump start trick I played Starcraft II yesterday totally maxed out at 2560x1600 for a couple hours and never had a single problem.

    I'm going to run Hardware Diagnostics after posting this but, in a nutshell, I'm wondering if anyone can suggest something else to try before I order a replacement PSU. It seems to me like that's the problem. Where should I get one?
  2. satcomer macrumors 603


    Feb 19, 2008
    The Finger Lakes Region
    I found if you use a Display Port to connect to a Display then disconnect the Diplay Port connection then try the boot up and see if that works, YMMV.
  3. Korican100 macrumors 6502a


    Oct 9, 2012
    ah mac pro 3,1. how many days will you ruin with your power supply issues...

    Power supply is going bad man. I've been there, other macpro3,1'ers have been there too. Sounds like you are about to go through it too bro.

    Like I always say, mac pro 3,1 is just like first gen of xbox 360 consoles. You are bound to run into hardware failure before having to get it fixed. RROD with the xbox, and power supply with the mac pro3,1.
  4. LorenK macrumors 6502

    Dec 26, 2007
    Just an FYI, I never turn off my 3,1, Yes, I am an energy wastral, but all things mechanical fail the more they get used, and I figure that by not using that power button, I avoid the heat up and cool down cycles that eventually destroy electronics. Do I know what I'm saying? I have no clue, I've probably rebooted about thirty times in five years, but my MP 3,1 just keeps going and going. If it ain't broke . . . .
  5. ggoerl macrumors regular

    Dec 18, 2007
    Really? never heard of that, first and only thing I've replaced that failed was my Nvidia GPU. Guess I've been lucky so far, *knocks on wood* I sure hope I don't encounter this problem.

    I hear ya, I'm the same way, I never turn mine off. I always just put it to sleep. The only time when I turn it off is when I'm gone for more than 2-3 days. My 3,1 has been through a lot. A road trip to canada where I used it there for a few months before bringing it back with me to California. So my 3,1 has some mileage.
  6. hualon thread starter macrumors 6502

    Feb 5, 2008
    Thanks for the replies! I have ordered a replacement PSU and will not shut down until it arrives. I bought it on eBay for $145.

    This machine is a real workhorse. I bought it new in 2008 and it has lasted longer than any other piece of technology I own. I've kept it updated with more RAM, SSD boot drive, updated video card, etc. but for the most part it has been a tank.

    I have been saving up for the new Mac Pro trashcan edition. Having just spent a couple hundred bucks on a replacement power supply, however, I'm rethinking my plan to sell the 3,1. Maybe I'll hold onto it a little longer or give it to my son.

    I'll post a followup when I get the replacement PSU in.
  7. OS6-OSX macrumors 6502a


    Jun 13, 2004
    Search online to replace the pwr supply. There is a video. You can save some more $. After pulling out the items in the optical bay, you pull out HD's 3&4 to get to the 4 screws holding in the pwr supply cage.

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