DisableTurboBoost

A macOS kernel extension (kext) for disabling CPU turbo boost to keep temperature (and fan noise) down.

Usage

Since System Integrity Protection (SIP) blocks unsigned kernel extensions, there are a few steps involved in enabling this kext:

1. Reboot Mac into recovery mode by holding down cmd+R when booting
2. While in recovery mode, open terminal and execute csrutil enable --without kext
3. Reboot back into normal mode
4. Open a terminal in the folder containing the kext and execute:

sudo chown -R root:wheel DisableTurboBoost.kext
sudo chmod -R 0755 DisableTurboBoost.kext
sudo kextload DisableTurboBoost.kext

Run kextstat |grep DisableTurboBoost to verify that it's loaded.

Run sudo kextunload -b no.vtek.DisableTurboBoost to unload the kext.

How it works

This small kernel extension will enable bit 38 of the MSR register MSR_IA32_MISC_ENABLE which causes the CPU to disable turbo boost.

There are some alternatives that enables bit 32 of MSR_IA32_PERF_CTL, but that didn't seem to have any impact on my system.

Take a look in the manual for more info.

Disclamer

I take no responsibility for whatever harm this kernel extension may cause your system. I use it myself without any issues, but I cannot guarantee it will work for you.

Troubleshooting

If you get this message when executing sudo kextload DisableTurboBoost.kext:

failed to load - (libkern/kext) not found; check the system/kernel logs for errors or try kextutil(8)

Try this command in stead: sudo kextutil -l DisableTurboBoost.kext

It will output something about invalid signatures, but the extension might still be loaded. Verify with kextstat |grep DisableTurboBoost.

Credits

The code was based on an outdated repo nanoant/DisableTurboBoost.kext.