RagingDragon (a@b.c) on 4/10/09 wrote:
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>slacker (s@lack.er) on 4/10/09 wrote:
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>>Vincent Diepeveen (diep@xs4all.nl) on 4/10/09 wrote:
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>>>David Kanter (dkanter@realworldtech.com) on 4/8/09 wrote:

>>Energy != Power, for reference.
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>To clarify: power = energy used per unit time. For example 1W = 1 J/s.
>

This is an important concept to make clear, many people equate peak power consumed (or produced to be dissipated) with energy efficiency, i.e. lower power = better energy efficiency. This is a false assumption.

As you state, power = energy per unit time, or Energy = P*time. One does not pay electric bills in terms of watts but WattHrs which is actually a unit of energy.

Peak power will dictate various thermal cooling designs and such, but total energy consumed determines energy efficiency. A server can have 20% higher peak power but if it completes the task in 50% less time will be more energy efficient.