Speedstep is fairly customizable and does three things:
1)Dynamicaly Adjusts Clockspeed according to demand
2)Dynamicaly Adjusts vCore according to Clockspeed
3)Drops processor into a deep sleep when idle (very low vCore)
It is also something you can turn off. It would let me get away with minimal cooling most of the time, if I needed performance I could disable speedstep and turn on an extra fan. Most of the time I could get away with a 500mhz processor and not be able to tell the difference, but when I'm encoding/transcoding video, gaming, or doing graphics work the extra processor speed makes a big difference. Hence the relivence of the question 😉
Peace,
will