Apple Fan Kext Mod

On my watercooled MDD G4, the Apple fan kext controls the 120 x 38mm fan that is attached to the radiator. This little piece of software would normally control the fan that is blowing on the rear hard drives. The Standard Apple 120mm fan now runs off the 5v supply


This enables the fans to start ramping up when the processor hits around 58 degrees. Well my watercooled mod will normally run around 34 degrees anyway. Even with the really adverse hot weather (32 degrees in England???!!) it wont go over 43 degrees so I decided to bring the ramp up stage down to around that area.

Below are the std Apple Fan Kext settings:



















Below are my modified settings:


















How to Modify

Every 256 you subtract from the number reduces the speed of ramp up by 1 degrees, so I reduced each value by 2816. Divide this by 256 & you get 11. So I reduced the point at which the fans cut in by 11 degrees, which is right where I wanted it.

The fan kext can be found in System/Library/Extensions/AppleFan.kext/Contents.

Open "info.plist" with Text Edit.

You will need your password to replace the kext. Make sure you back up the original kext & copy the kext to the desktop to work on, thus, creating your new one. You will need to repair permissions when you have replaced the kext for it to work. You will also want to keep a copy of your new kext as you never know when Apple will monkey around with this in an update.


This mod only works on MDD's & G5's, as you need the onboard thermistor on the processor for the kext to be loaded.


But it worked a treat!


Many thanks go to Atomic at bits & pieces to pioneer this mod

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