Mac Pro 5,1 Won't Power

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Level 1

22 points

Mac Pro 5,1 Won't Power

Hello Friends ::

I've been following threads like this Mac Pro 5.1 won't power up as I'm trying to troubleshoot a Mac Pro 5,1 (2012) that won't boot.

There's no lights on the motherboard, no click or fans starting when power button is pressed. The diagnostic buttons don't give any feedback.

Power supply has been replaced two-weeks ago (by Apple Store). This fixed the issue for a short period of time here are other things that I've tried

Swapped video cards
Swapped power cords
Used different power receptacle
Replaced Motherboard battery
Removed/replaced all RAM
Removed/replaced Processor Tray

I'm going to see if I can find a new Processor Tray to swap out, but I'm not feeling optimistic.

If anyone can share some insight, I'd appreciate it.

Thank you!

Marc

Posted on Oct 10, 2018 6:38 AM

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Answer 1

Top-ranking reply

Grant Bennet-Alder

Level 10

140,789 points

Oct 10, 2018 8:18 AM in response to MarcStress

The "approved method" for this debugging is to strip your Mac down to the smallest remaining components that can produce a fan-on, blinking power-on light, or chime. That means remove all drives, all DVD Readers, all slot cards, and all RAM memory.

While the graphics card is out, check the long-life Lithium non-recharging coin cell battery for nominal 3 Volts in hand. CAUTION: the holder is very delicate. These BR2032 batteries can be hard to find, but a practical substitute is the CR2032 battery used in car key fobs and garage-door opener controls.

Once you have fan-on, look for blinking power indicator. A pattern of three blinks indicates "not enough working RAM to start up". Once you have RAM, you will get the chime. Once you have the chime, you can add the graphics card.

Proceed slowly and methodically in VERY small steps.

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Answer 2

Oct 10, 2018 9:21 AM in response to MarcStress

Sounds like another dead power supply. However with two dead in such short time it seems something else maybe wrong which is killing the power supplies.

Your power supply will have a warranty even if the rest of the Mac Pro does not.

For what its worth I recently had a PowerMac G5 die and it was the power supply. Like your Mac Pro it was totally dead, no clicks or lights. I swapped the power supply and it has been fine since.

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Answer 3

MarcStress Author

Level 1

22 points

Oct 10, 2018 9:28 AM in response to John Lockwood

Agreed @John Lockwood. It seems that the power supply has failed again, and it points me to the possibility that there's something causing this failure.

Because I just had an Apple Authorized repair, I brought it back for them to fix. Good news is I won't have to pay for another power supply, or the labor (or my time) to do it. They'll have it on their bench to determine what the root cause is.

I've had more than a dozen of these machines from 3,1 forward the Blue and White towers, 1,1s and forward and never experienced any kind of failure like this.

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Answer 4

MarcStress Author

Level 1

22 points

Oct 10, 2018 9:31 AM in response to Grant Bennet-Alder

Thanks. Grant. I did replace the motherboard battery, and swapped out multiple components to try to get a POST chime, to no avail. Because the previous repair was done at Apple, I'm having them pick it up and re-replace the power supply and hopefully solve the larger issue of why this thing keeps eating components.

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Answer 5

MarcStress Author

Level 1

22 points

Nov 1, 2018 7:37 PM in response to MarcStress

Closing the loop on this one...

The problem ended up being a failed backplane board in the MacPro.

Replaced the backplane board and the machine works like a champ.

Thanks to all who chimed in with helpful comments here!

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Mac Pro 5,1 Won't Power

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