MP 1,1-5,1 Classic Mac Pro (4,1 and 5,1) Logic Board cross compatibility

[jannikmeissner]

I tried searching and didn't find anything. Are those logic boards (flashed with the 5,1 firmware) interchangeable? Or in other words, is it actually possible to fix a broken either a 5,1 or 4,1 Mac Pro with a replacement logic board out of the other, with all other parts remaining in the same unit?

 

[fhturner]

The backplane board and processor tray need to be of the same model identifier (4,1 or 5,1) and therefore SMC version. Otherwise the fans will run at max RPM.

 

[StuAff]

Having tested out a couple of 4,1 boards in a 5,1, I would add that you certainly do not want to think 'the noise won't be that bad' or some such. Very loud indeed.

 

[jannikmeissner]

Which other component needs to match to the Logic Board? The CPU Tray or the PSU?

 

[StuAff]

Which other component needs to match to the Logic Board? The CPU Tray or the PSU?

Processor tray. PSU, AFAIK, is identical.

 

[tsialex]

The backplane board and processor tray need to be of the same model identifier (4,1 or 5,1) and therefore SMC version. Otherwise the fans will run at max RPM.

Model identifier it's the same after EFI cross flash, so, this effectively means nothing with MP4,1/5,1 platform.

It's the model year that have different, and not upgradeable, SMC releases and what's you need to check.

CPU trays and backplanes have to match the SMC version:

SMC version:	Model year:
1.39f05	early-2009
1.39f11	mid-2010
1.39f11	mid-2012

You can mix match mid-2010 with mid-2012, but not with early-2009.