Intel Turbo Boost is a technology implemented by Intel in certain versions of its processors that enables the processor to run above its base operating frequency via dynamic control of the processor's clock rate. Processor generations supporting this feature are based on the Nehalem (Turbo Boost 1.0), Sandy Bridge (Turbo Boost 2.0), Ivy Bridge, Haswell, Broadwell, Skylake and Broadwell-E (Intel Turbo Boost Max 3.0) microarchitectures, while the examples of Turbo-Boost-enabled processors are the Core i5 and Core i7 series. Turbo Boost is activated when the operating system requests the highest performance state of the processor. Processor performance states are defined by the Advanced Configuration and Power Interface (ACPI) specification, an open standard supported by all major operating systems; no additional software or drivers are required to support the technology. The design concept behind Turbo Boost is commonly referred to as "dynamic overclocking".
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The increased clock rate is limited by the processor's power, current and thermal limits, as well as the number of cores currently in use and the maximum frequency of the active cores. When the workload on the processor calls for faster performance, and the processor is below its limits, the processor's clock will increase the operating frequency in regular increments as required to meet demand. Frequency increases occur in increments of 133 MHz for Nehalem processors and 100 MHz for Sandy Bridge, Ivy Bridge, Haswell and Skylake processors. When any of the electrical or thermal limits are reached, the operating frequency automatically decreases in decrements of 133 or 100 MHz until the processor is again operating within its design limits. Turbo Boost 2.0 was introduced in 2011 with the Sandy Bridge microarchitecture, while Intel Turbo Boost Max 3.0 was introduced in 2016 with the Broadwell-E microarchitecture.
History
An Intel November 2008 white paper discusses "Turbo Boost" technology as a new feature incorporated into Nehalem-based processors released in the same month.
A similar feature called Intel Dynamic Acceleration (IDA) was available on many Core 2 based Centrino platforms. This feature did not receive the marketing treatment given to Turbo Boost. Intel Dynamic Acceleration dynamically changed the core frequency as a function of the number of active cores. When the operating system instructed one of the active cores to enter C3 sleep state using the Advanced Configuration and Power Interface (ACPI), the other active core(s) dynamically accelerated to a higher frequency.
Intel Turbo Boost Technology Monitor, as a GUI utility, could be used to monitor Turbo Boost; this utility has reached the end-of-life state by no longer supporting Intel processors released after Q2 2013, and is no longer available.
Example
For Core i7-920XM, normal operating frequency is 2.0 GHz. Turbo is indicated as: 2/2/8/9 in which the first number is the number of times of 133⅓ MHz supported when four cores are active, the second number is the multiplicity of 133⅓ MHz for three cores, the third number is for two cores, and the fourth number is for one active core.
Subject to limits on temperature, current and power consumption, the processor can increase its clock speed (from a base frequency of 2.0 GHz) in steps of 133⅓ MHz to:
For Core i7-2920XM, normal operating frequency is 2.5 GHz. Turbo is indicated as: 7/7/9/10 in which the first number is the number of times of 100 MHz supported when four cores are active, the second number is the multiplicity of 100 MHz for three cores, the third number is for two cores, and the fourth number is for one active core.
Subject to limits on temperature, current and power consumption, the processor can increase its clock speed (from a base frequency of 2.5 GHz) in steps of 100 MHz to: