CPU under full load with turbo boost worth the extra energy/electricity?

Say I have a set of number to crunch or video to encode over the night. The duration do not matter as long as it finish before I wake up.

Would I save a bit on my electricity bill if I disable turbo?

Assume computer will be on regardless so other component don't get into the equation.

 

Define save. If you are aiming at saving several dollars, no. Although it probably depends on where you live. In America, in my state, my supplier charges me at the most 9 cents to a kwh. The most power hungry laptop CPU does not cross 60W. You'd need to run that full Turbo for over 16 hours to save 9 cents where I live.

 

In theory: Power draw increases exponentially with clockspeed assuming load is the same. Turboboost tends to spike the CPU with more voltage than actually required at that clockspeed to guarantee stability.
In practice: Laptop CPUs use so little I doubt it makes a meaningful difference, if we were discussing the i7-3960X or a couple of Octa Xeons then it might be meaningful.

 

Thanks I realize computer use not much energy compare to appliances.

How about encoding video to smaller file, would it justify its electricity cost.(versus buying new hard disk}

 

In general, when a CPU has a task to do, it it best to get that task done as quickly as possible and then either have the CPU get back into one of the low power C States like C6 or better yet, once your computer is finished working, turn it off. That's the best way to save power. Slowing it down is the last thing you want to do.

Power Optimization – a Reality Check
http://www.cs.berkeley.edu/~krioukov/realityCheck.pdf

 

Actually power consumed increases linearly with clock speed and exponentially with voltage. So at double the clock speed, you would at most consume double the power. Even with the 3960X, the TDP is only 150W. Assume that the CPU consumes a max of 250 Watts. Even so, assuming that the user has already reached the top tier for his electricity usage for the month and assuming a US average of 15 cents per kWh, you would still end up spending only about 60 cents an hour. You keep it on all night for 12 hours, that's still about $7.2. This is assuming the CPU runs at max clocks for all those 12 hours.