|Don't confuse frequency with clock speed. Your CPU clock speed is 2.66GHz. It has a base frequency of 133MHz & a default multiplier of 20x. The base frequency does not change but the multiplier is either raised or lowered based on load. |
"I think the one core thats on is overclocking"
What do you think TurboBoost does? When it kicks in, the CPU multiplier is raised & that effectively overclocks the CPU.
SpeedStep (EIST) does exactly the opposite. It lowers the CPU multiplier, effectively underclocking the CPU under light or no load conditions. This conserves battery power & keeps the CPU running cooler.