Intel Turbo Boost Technology

Intel Turbo Boost Technology feature temporarily boosts CPU performance by increasing frequency of one or more cores. How much the frequency is increased depends on microprocessor type, the number of inactive cores, i.e. cores in states C3 or C6, and current thermal conditions, which, in turn, depend on the CPU load, quality of thermal solution, ambient temperature, and other factors. The processor may operate in Turbo Boost mode as long as it stays within its thermal (TDP and maximum temperature) limits. The frequency is increased in steps, where 1 step is 133 MHz. On desktop Intel microprocessors the frequency can be lifted by 1 - 5 steps, or 133 - 667 MHz, while some mobile CPUs support up to 10 steps, or 1.33 GHz boost. As a note, not all CPUs support those 5-step or 10-step boosts, and they may only add mediocre 1 or 2-steps to base frequency. To see the maximum frequency increase for you CPU please check the notes section on S-Spec pages on this site.

The Turbo Boost is activated and deactivated automatically in hardware. If this feature is not desired then it can be turned off in BIOS. The Turbo Boost Technology was introduced in Core i7 microprocessor family, and, as of July 2010, it is incorporated into the following families:

Core i5
Core i5 Mobile
Core i7
Core i7 Extreme Edition
Core i7 Mobile
Core i7 Mobile Extreme Edition
Xeon

Unlike Dual Dynamic Acceleration feature, which was used in older generations of quad-core processors and could boost frequency of only two CPU cores, the Turbo Boost Technology may increase frequency of all 4 cores.