Maximum Efficiency: Build A 25W Performance PC Using Core i5

Test Setup And Power Consumption Results

Results: Idle and Peak Power

We started off at 33W idle power, which is low but not revolutionary. We then exchanged the high-power PSU with a more efficient one.

The most important thing in this measurement is the fact that we aligned the PSU’s output to the expected system power consumption as much as possible. A 750W PSU running at only 40W load would be pretty inefficient. For this reason, the idle power decreased from 33W to only 26W. Even our small voltage decrease didn’t make much of a difference . The only other step that had an impact was the use of Toshiba’s 640GB 5,400 RPM hard drive instead of the high-performance WD VelociRaptor. Ultimately, we dropped from 33W to 23W with only two component changes. This is a 30% reduction in idle power.

Peak power doesn’t differ that much, as even the 750W Silencer power supply is operating at much more efficient levels. This is why its replacement doesn’t make as much of a difference under a heavy load. The voltage tweak, however, did make a difference of 4W. Another 2W could be saved through the more efficient hard drive.

Overall, the total impact on peak power is less significant than the change in idle power. This is where a desktop-class build will be significantly more power-hungry than a machine centering on Intel's Atom CPU. However, most desktops will spend little time using this much juice. In return, they also finish the same tasks in less time.