TurboTune is a macOS kernel extension for tuning of Turbo Boost settings.

TurboTune enables fine-grained control of Turbo Boost behavior on Intel processors. Instead of simply turning Turbo Boost on/off, it allows creating a custom turbo curve to balance performance and energy efficiency.

• The kernel extension changes Turbo Boost settings by modifying model-specific registers (MSR), which may void your CPU's warranty and cause permanent damage to the CPU. Proceed with caution.
• The kernel extension is unsigned. System Integrity Protection (SIP) needs to be disabled to load the extension.

You need to create a custom turbo curve by modifying the MSR_TURBO_RATIO_LIMIT field in Info.plist file before loading the kernel extension. MSR_TURBO_RATIO_LIMIT is a model-specific register on Intel processors that controls the Turbo Boost settings. The format of the register can vary between processors models. Please refer to Intel® 64 and IA-32 Architectures Software Developer’s Manual Volume 4: Model-Specific Registers to determine the format for your processor model.

Core i5-8259U is a quad-core processor with a 2.3 GHz base frequency, and a default turbo frequency limit between 3.8 GHz (when a single core is active) and 3.5 GHz (when all four cores are active). For this processor, MSR_TURBO_RATIO_LIMIT is a 64-bit register where the N-th lowest byte represents the turbo frequency limit when N cores are active (frequency = byte value x 100 MHz). With the default policy, the register has a value of 0x24252626.

Suppose we would like to save power but do not want to turn off Turbo Boost entirely (which would limit all cores to the base frequency of 2.3 GHz), we can define a custom turbo curve with, for example, a single-core turbo of 3.0 GHz, and an all-core turbo of 2.7 GHz. With this policy, the value of the MSR_TURBO_RATIO_LIMIT register is 0x1B1C1D1E. To enable this policy, change the MSR_TURBO_RATIO_LIMIT field Info.plist to 454827294 (0x1B1C1D1E in decimal) and load the kernel extension.