MP 1,1-5,1 Help! Mac Pro 5,1 to 4,1 Downgrade for CPU Tray Change

[damob2]

Hi everyone,

If anyone could help that would be great!

I have a 4,1 Mac Pro Single CPU that we've flashed to 5,1 and is running mojave well with a x5690 etc.
So its updated to Mojave and BootRom 144.00.00

I have bought a dual cpu core from another 4,1 and plan to put in another x5690 and more ram etc.
For this I have to flash the new cpu tray with the computer because at the moment when I insert it the computer refuses to boot etc. So I created a clean El Cap install and changed back to original CPU to change back to a 4,1 so I could then upgrade the dual core to 5,1. The Firmware hack tool doesn't work for me - no matter what EFI download I grab from Apple, either 1.4 or 1.5.

So we went to investigate any methods that could get us back to a 4,1 bootrom / firmware so I can use the dual CPU tray.
Any help or ideas from anyone would be great, but just knowing its not possible would also be useful.

Things I've seen is boot into flashrom in linux to edit the bootrom? Use romtool to grab firmware from installs of macOS

I think grabbing a 4,1 backboard that hasn't been flashed to 5,1 and my dual cpu tray should boot together but that is a last resort as we are stuck.

So any help would be great guys - thanks in advance.

 

[tsialex]

Hi everyone,

If anyone could help that would be great!

I have a 4,1 Mac Pro Single CPU that we've flashed to 5,1 and is running mojave well with a x5690 etc.
So its updated to Mojave and BootRom 144.00.00

I have bought a dual cpu core from another 4,1 and plan to put in another x5690 and more ram etc.
For this I have to flash the new cpu tray with the computer because at the moment when I insert it the computer refuses to boot etc. So I created a clean El Cap install and changed back to original CPU to change back to a 4,1 so I could then upgrade the dual core to 5,1. The Firmware hack tool doesn't work for me - no matter what EFI download I grab from Apple, either 1.4 or 1.5.

So we went to investigate any methods that could get us back to a 4,1 bootrom / firmware so I can use the dual CPU tray.
Any help or ideas from anyone would be great, but just knowing its not possible would also be useful.

Things I've seen is boot into flashrom in linux to edit the bootrom? Use romtool to grab firmware from installs of macOS

I think grabbing a 4,1 backboard that hasn't been flashed to 5,1 and my dual cpu tray should boot together but that is a last resort as we are stuck.

So any help would be great guys - thanks in advance.

Trays don't have BootROM firmware at all. BootROM firmware is on a SPI flash located on the backplane.

2009 CPU trays work for MP4,1 or MP5,1 firmware, don't matter.

The only thing that differentiate logically a CPU tray between years is the SMC version:

Mac Pro year model:	SMC version:
early 2009	1.39f5
mid 2010	1.39f11
mid 2012	1.39f11

Hardware wise, 2009 dual CPU trays use de-lidded Xeons while 2009 single and both the 2010/2012 single and dual CPU trays use lidded Xeons.


The SMC firmware is not upgradeable and you can't use a 1.39f5 backplane with a 1.39f11 tray, or vice-versa. With a SMC mismatch you will have all the Mac Pro fans working at 100% RPM, full time.

You don't have to do anything to the 2009 dual CPU tray for it to work with a 2009 Mac Pro flashed with MP5,1 firmware.
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If your 2009 dual CPU tray don't work with your MP4,1>5,1 Mac Pro, the tray is damaged. You can't upgrade or downgrade a tray and trays works for both MP4,1 or MP5,1 firmwares.

 

[Snow Tiger]

tsialex is correct .

You cannot change SMC version of the components in your Mac Pro . Well , you could solder in a new or reflashed firmware chip , I guess if you are a hobbyist . But most users would not want to do that ...

You can change its Model Identifier from Mac Pro 4,1 to 5,1 and vice versa with the Netkas flashing tool . That should change its old style Boot ROM version . Possibly with Boot ROM versions 138 or later , this might no longer be true . ( I haven't rolled back a 5,1 to a 4,1 in a long time ) .

But be careful , since if your CPU Tray has six core chips and you flash your Mac back to Mac Pro 4,1 Model Identifier your Mac will not boot , as the processors will no longer be supported .

That said , just maybe your Dual CPU Tray is broken . Or , it is suffering an Over Temp ( OT ) situation on a CPU or the North Bridge Chip , which will prevent a start up . CPU OT are indicated with a diagnostic LED on the logic board . Xeons are hard to kill and maybe all they need is fresh thermal paste . Remove the dry paste and re-thermal paste both CPUs with Arctic MX4 .

There is no North Bridge OT indicator LED with the Mac Pro . You just might want to examine the Tray's North Bridge ( NB ) heatsink's fasteners to verify they are still securing the heatsink in place properly . Also , re-thermal paste the NB chip with fresh Arctic MX4 paste as it will be dry by now . / That should help cool your Tray and allow her to boot .