2009 Mac Pro running with fans at full speed after CPU tray upgrade 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!
You must use the original tray from the 4,1.  Cannot put 4,1 tray in 5,1 or vice versa.   If you do, you cannot control the fans.

The firmware upgrade changes the Model from 4,1 to 5,1 but does not change the SMC System Version or the SMC Processor Tray version.  These must match. These should both be 1.39f5 with an original 4,1 or 1.39f11 with an
original 5,1.