Great answers on this thread. Love the Knight Rider pic. But to reel this in and be a little serious for a sec: this is Intel's solution to the fact we had to compromise raw GHz for more cores.
Some of the original Pentium 4 processors could run at over 3GHz, but processor speed dropped soon thereafter to make way for smaller transistor sizes and more cores. The CPUs got more units of work done in a given amount of time, but one task might take longer because of the slower speed.
Now, with Turbo Boost the operating system is able to shut off individual cores on the chip and crank up the speed on the other ones, because some tasks just can't be broken down into parallel steps. They need that raw horsepower. There are some caveats, though:
- the chip can't be too hot already, because the increased clock speed is going to heat up the active parts of the chip even more
- the chip can't be drawing too much power already, because a lot of the power a processor uses gets released as heat
- and, the chip needs to have active cores that aren't already shut down
This all happens on the fly. There's no need to do anything manually to manage it.