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!

  • Have you tried the tried and true NVRAM and SMC reset?
    – Allan
    Dec 19, 2016 at 21:40
  • I've reset the PRAM, and I've followed Apple's instructions for SMC reset (although since they pretty much amount to unplug it and plug it in again, it could be argued that an SMC reset is part of the tray upgrade!)
    – headbanger
    Dec 19, 2016 at 21:42
  • 1
    The author of the source of this firmware upgrade stares: I have tested this myself, on both 2009 and 2010 Mac Pro models. Perhaps the 2012 model you're working on needs a newer firmware upgrade, even though this one (mostly) works. From the symptom the MacPro is presenting, the fans are getting no guidance from the heat (and other) sensors about how fast to turn, so are blindly going all out to protect their priceless CPU from getting cooked.
    – IconDaemon
    Dec 19, 2016 at 22:33
  • I think @IconDaemon is on to the main culprit - the firmware fails in a state where the blowers go to max. When something isn't correct or changes - the blowers will go to max to save the system in case of an unexpected change.
    – bmike
    Dec 19, 2016 at 23:57
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    Changing the entire tray could lead to problems. When you upgraded the tray, which firmware did you upgrade, the Boot Rom version or the SMC version? You need to upgrade both for this upgrade to work. The new boot rom version should be: MP51.007F.B03. The new SMC firmware should be 1.39f11. If you go to About this Mac -> System Report -> Hardware Overview, you'll be able to see this information. For example, my Mac Pro 4,1 (5,1 firmware) has boot rom version 51.007F.B03. However, because my tray is still the original tray, my SMC Version is 1.39f5.
    – NoahL
    Dec 20, 2016 at 2:00

2 Answers 2


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.

I think I can answer the question now. There was a misunderstanding regarding the firmware upgrade tool to upgrade a Mac Pro 4,1 to 5,1. The firmware upgarde tool does not update the SMC firmware, but installs a different boot rom version. Mac Pro 4,1 (2009): MP41.0081.B07 (original) Mac Pro 5,1 (2009): MP51.007F.B03 (upgraded)

The system and CPU board SMC version remains at 1.39f5 for the MacPro 2009. A Mac Pro 2010 uses 1.39f11. After upgrading a Mac Pro 4,1 to 5,1, the SMC firmware was still 1.39f5. SMC mainly deals with temperatures and fan speeds. It is important that the SMC version of the CPU and system are the same. So to answer my question, it is not possible to use a 5,1 CPU board in a 4,1 system or vice versa. I'm not sure what happens when mixing them, but apparently the system does either not boot or the fans go crazy, perhaps depending whether you put a 5,1 cpu board into a 4,1 system or vice versa. Here are some links I found meanwhile for reference:
http://forum.netkas.org/index.php?topic=852.0;wap2 http://forum.netkas.org/index.php/topic,852.375.html http://arstechnica.com/apple/2011/05/firmware-hack-can-transform-a-2009-mac-pro-into-a-12-core-monster/

Btw, the firmware upgrade tool 4,1 to 5,1 shows error 5570. That is because Apple changed the location of the 5,1 efi firmware image. You can however download the 5,1 firmware from Apple and simply mount the disk image prior to running the tool and it will work fine. Then shutdown the system and hold down the power button until a tone occurs, then the system will restart and show a progress bar to update the firmware.


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.

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