When any of the electrical or thermal limits are reached, the operating frequency automatically decreases in decrements of 133 MHz/100 MHz until the processor is again operating within its design limits. Frequency increases occur in increments of 133 MHz for Nehalem microarchitecture processors and 100 MHz for Sandy Bridge microarchitecture processors.

When 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. 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.

Turbo boost is supposed to boost the CPU speed within thermal limits, if only one core is in use but the thermal limit is not met then Turbo Boost will boost the CPU speed for short periods.īy trying to load all 4 cores you are most likely surpassing the thermal limit and thus preventing it from activating.

How to enable turbo boost core i5