MP 1,1-5,1 Mac Pro 5,1 hardware issues: won’t boot, fans go to 100% full blast

[e^2]

Something has happened to my Mac Pro 5,1 and it has decided it will not boot. I have downloaded the technical service manual and am trying the minimum configuration testing. With the CPU tray installed (but no CPU) the system powers on and fans spin to 100%. The only diagnostic LEDs are PWR OK and 5V standby. When I hold down the power button to shut off the machine, the CPU A OVERTEMP LED is lit on the backplane.

Anyone know what it might be? I’m guessing it’s either the backplane, power supply, or CPU tray.

 

[MIKX]

Is it a SINGLE or DUAL CPU 5,1 ? - it;s always helpful if you tell us EXACTLY which cMP you have, which bootrom version, which Mac OS you currently have installed. etc. 🤔

Shut down, remove the CPU Tray .. . check to see if the Northbridge Heatsink spring rivets are unbroken.

Have you ever de-dusted CPU tray and the intake & Exhaust fans ? 🤭


After checking the above do this . .. .

 

[e^2]

single. I’ve already stripped the machine down and cleaned everything. I put it back together and ran AHT. It came back perfect.

I shut it down for 24 hours then came back to install a new GPU and that’s when it stopped working.... First boot with the new GPU card, it never came up properly. Just fans at 100%.

Is it a SINGLE or DUAL CPU 5,1 ? - it;s always helpful if you tell us EXACTLY which cMP you have, which bootrom version, which Mac OS you currently have installed. etc. 🤔

Shut down, remove the CPU Tray .. . check to see if the Northbridge Heatsink spring rivets are unbroken.

Have you ever de-dusted CPU tray and the intake & Exhaust fans ? 🤭


After checking the above do this . .. .

View attachment 895354

 

[MIKX]

Do you always " hold down the power buton " TO SHUT IT DOWN . . or only since the fans have been ramping up ?

Alaso Can you takes a scrcreenshot of your Hardware list in "Mac hardware" in yout mac Pro's System Report ( blur out your cMP's serial number
[automerge]1582390794[/automerge]

 

[e^2]

Do you always " hold down the power buton " TO SHUT IT DOWN . . or only since the fans have been ramping up ?

Alaso Can you takes a scrcreenshot of your Hardware list in "Mac hardware" in yout mac Pro's System Report ( blur out your cMP's serial number
[automerge]1582390794[/automerge]

The machine will not boot, will not even play a boot chime. It is a brick. It is in minimum configuration testing so there is no disk or GPU in it currently.

Of course I do not hard power cycle it in the normal case.

 

[e^2]

The machine will not boot, will not even play a boot chime. It is a brick. It is in minimum configuration testing so there is no disk or GPU in it currently.

Of course I do not hard power cycle it in the normal case.

The backplane I ordered from eBay arrived a few days ago and I installed it tonight. It boots. I’m guessing the original backplane had some issues. Perhaps it’s was the SPI flash, or perhaps the power draw from the new GPU caused issues.