The fans on my 2009 Mac Pro are running at full speed after upgrading the CPU tray to the tray from a 2012 12 core. Temperature monitor reports that the CPU temperatures are steady 32° and 34°c, and all other temperatures are within that range, and other than the howling noise my Mac Pro is running perfectly normally.
The firmware has been upgraded as per this site http://forum.netkas.org/index.php/topic,852.msg5004.html#msg5004 and the OS is Sierra.
I've currently dropped back to the factory fitted 2.66GHz quad, albeit with the same firmware, and all is quiet and peaceful again.
I can't run AHT or diagnostics because neither are installed on the machine – and I don't know what I've done with the installer disk. I have reset the SMC and NVRAM to be sure it's not a simple software / configuration fix.
Can anyone suggest a fix? I'm at a loss because the temperatures report as being entirely healthy!
Best Answer
Copied directly from Apple Discussions: Installing MacPro5,1 Processor Tray into MacPro4,1
[I can claim nothing but Google-Fu on this one. My SMC is the same as NoahL's 1.39f5 so I can only presume mine has the original 4,1 daughterboard, with 3.46GHz Westmeres added after-market. I bought mine ready-upgraded, so it's not a process I've ever done myself.]
From this, though, it would appear that the 2 versions of the CPU/RAM daughterboard are not interchangeable.