MP 1,1-5,1 Power issues on Mac Pro 5.1 running monterey

[JoeStrummer]

Hello

I have a 2010 Mac Pro 5.1 that is running Monterey using OpenCore. Been working very happily for at least the last 6 months, nothing has been changed on the system. Recently it has been shutting down suddenly. It shuts down and then won't reboot, power button unresponsive. Then later, maybe the next day, it will power on again and run for a while before just shutting down again.

I bought a replacement Power Supply and fitted it. It worked for a couple days then same thing, it just shuts down

I replaced the CPU tray with a known working CPU and same problem

I have removed all drives and same problem

I have followed the 'tech service manual' of breaking down the machine to Minimum Configuration but that didn't really answer anything

If anyone has any suggestions that would be great, thank you

 

[krakman]

Your back plane is dying.

I guess there is a failing component on the back plane such a capacitor, which can dry out, or corrosion of electrical contacts.

This is like having electronic cancer.

I had several Mac Pros die on me in the same way you describe.

I had a small office in a building next to the sea. Humidity and salty air was the killer combination.

You could try removing the back plane and washing it with a soft paint brush and isopropyl alcohol.

 

[JoeStrummer]

Thanks krakman
Do you know whether the back plane of a 2010 Mac Pro 5.1 is directly replaceable with the back plane of a 2009 Mac Pro 4.1?
I have an old 2009 Mac Pro 4.1 that I am not using. Maybe I can just pull the back plane from it and use it in the 2010 5.1?

 

[tsialex]

Thanks krakman
Do you know whether the back plane of a 2010 Mac Pro 5.1 is directly replaceable with the back plane of a 2009 Mac Pro 4.1?

No, it's not compatible.

I have an old 2009 Mac Pro 4.1 that I am not using. Maybe I can just pull the back plane from it and use it in the 2010 5.1?

SMC firmware version 1.39f5 of 2009 MacPro is incompatible with the 1.39f11 SMC firmware of the 2010/2012 Mac Pros. The SMC firmware is not user or techinician upgradeable.

If you mismatch the backplane and CPU tray, all the fans will run at fail-safe mode with full RPM and without software control. Only useful for tests/diagnostics, no one in the right mind will want to be near the jet engine sounding Mac Pro…

 

[JoeStrummer]

Thanks tsialex

 

[krakman]

I have an old 2009 Mac Pro 4.1 that I am not using.

Speak with tsialex about boot rom service for your 4.1 to make it a 5.1

you won't be able to swap the cpu boards but you can move over hard drives and RAM & gpu.

AFIK the 4.1 used de-lidded cpus so there is an extra step involved if you transfer over your CPUs, or just buy some cheap ones from Ebay.