For all of the performance tests, we disable all power-saving technology in order to give us a consistent set of results, and to give us best-case performance numbers - even though technologies such as Intel's SpeedStep might only take microseconds to kick in, that can make a difference in some tests.
However, for the power consumption tests we re-enable everything in order to get a real-world power draw. The power draw is measured via a power meter at the wall, so the numbers below represent the total system power draw from the mains, not the power consumption of the CPU itself. Measuring the power draw of any individual component in a PC is tricky to impossible to achieve.
We've also included the Raspberry Pi's claimed power draw of 3.5W for the Model B for comparison - this number is generally accepted although it should be taken as a general guide.
Idle Power Consumption
For this test, we leave the PC doing nothing but displaying the Windows 7 desktop (with Aero enabled) for a few minutes and record the wattage drawn from the wall via a power meter.
Power Consumption (Idle)
Windows Aero enabled
Raspberry Pi (claimed power consumption)
Intel NUC D33217CK
Intel Core i3-3220
Intel Core i5-3570K (discrete GPU)
Watts, lower is better
Load Power Consumption
To generate a realistic load power consumption figure we need to load both the CPU and GPU portions of the processors. To do this we used prime95 to load the CPU and Unigene's Heaven benchmark to load the GPU.