MacPro early 2009 isn't getting power.

Hello, My MacPro is the early 2009, A1289. The dual CPU one.


It's been a long time I try making him work again. I already try to make the minimum config, no processor tray and cage with everything that have to come out, shorting the sys power on the board, but nothing. The 5v STBY is always on when diag led is press, the PROCA and B led power on for 0.5 sec when pug and unplug. Today I tried looking onto the PSU voltage with a multimeter and the pinout of the PSU. When I short the pin 4 and 14 I hear a click and the 12V is here, so the PSU isn't totally wreck. But yea, when pug back in nothing make it spin to life. I tried with the other MacPro. I have (the same) to switch the processor board, but no spin to life after that. And when I put the processor board of the faulty one in the working one it spin to life normally, it isn't the graphics card cause work on the good one.


The backboard is receiving power, the psu is good when the right pin is short, the processor board isn't faulty, could be the backboard half-break? But there are no signs of damage. Never left in dust, well take care of. No sign of water or electrical damage.


the reason i'm trying to make it work again is that i'm passionate about computers and i'm going to make a living out of it. for my homelab this mac is a good start for what i want to do right now.

Posted on Apr 7, 2025 3:47 AM

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Apr 7, 2025 6:49 AM in response to UnVeluX

that suggests both processors are good.


when your Mac refuses to power on, and it has been disconnected from power recently, check the small coin cell battery half-hidden behind the graphics card slot.


it should be higher than 3.000 volts when checked in your hand, not in the circuit.

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Apr 7, 2025 7:15 AM in response to UnVeluX


the power button is on the front panel board, on a cable off the main board. it is surprisingly difficult to access.


But shorting the correct pads on the mainboard should do the same as the power button.


Consider swapping power supply modules between your two Macs. It sounds onerous, but is actually not that difficult.


And again, you want to know BOTH results.

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Apr 7, 2025 3:17 PM in response to Grant Bennet-Alder

I MANAGE TO MAKE IT WORK. After disassembling everything and just plug the backboard in the CPU board and so it boots. After inspecting it I found a resistance that was knocked out and could have caused a short right next to the Intel chip of the back board. I'm now reassembling it and i keep you informed

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Apr 7, 2025 3:38 PM in response to UnVeluX

IT WOOOORKS, everything plugs back in and no issues. Just a short of a little dumb thing. I'm so happy, now that my two macs are working I will double my home lab efficiency. Thanks you Grant Bennet-Alder you're a life saver, I wouldn't get the strength to make all of those check. (sry for my english i'm not native, thanks from France)

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Apr 7, 2025 4:43 PM in response to Grant Bennet-Alder

WOW, impressive, you're dedicated to helping others. You are a godsend to us, let's stop the flattery. A big thank you to you for helping me so much, know that I wouldn't forget it. Have a nice day or evening. And let's hope the future is good for us. (wrote that on DeepL, i'm starting to fell tired, so i'm lossing my english level) (from C1 to B1) ISHHH. ur so kind i want to be friend with u. now it's over for me, i have to leave BYEEEE.


thanks again

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MacPro early 2009 isn't getting power.

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