iXBT Labs compared the energy consumption of Ivy Bridge and Sandy Bridge

Measuring electrical quantities of PC enclosure is a curious task. It's particularly interesting and informative to measure platform's consumed power and energy consumption, two different things people tend to mix up. Let's clear the definitions first: power is the rate at which energy is produced or consumed (in our case). Power is measured in watts, while energy is usually measured in kilowatt hour (watt hour in our case). You might also want to read the article on Wikipedia.

Tasks one can load a computer with differ based on how much work is done in a unit of time and how this rate changes over time.

Judging by the amount of work done, we can say there are 'constant' and 'variable' tasks. Some of the constant tasks are regular video playback, data compression/decompression, video encoding and transcoding. One example of a variable task is games, where the amount of work done depends on PC hardware and may differ greatly. In this last case, measuring energy consumption as such is kind of meaningless, because we'll be measuring how much energy is spent on different amounts of work.

  Consumed Power, Energy Consumption: Ivy Bridge vs. Sandy Bridge