By using CPU-Z or Intel’s overnamed “Intel(R) Turbo Boost Technology Monitor 2.0” I can see that when my CPU is idle it drops to very low speeds, and when it is under heavy load it actually spikes up to around 3.0 GHz (2.993 GHz according to CPU-Z, which is probably more trustworthy than Intel’s potentially biased CPU speed monitor). The actual peak CPU speed depends on the overall load of the CPU and GPU, which means that if you optimize your code really well then you might push the CPU so hard that it can’t overclock itself quite as much. const double qpcRate = (double)GetQPCRate(); // Measure the CPU speed reported by __rdtsc() when the