Noise levels
Noise levels were measured at idle and under load using an Extech 407727 Digital Sound Level meter placed 1" from the rear of the system and out of the direct path of airflow. You'll notice "missing" results for some of the PSUs at idle. We've omitted them because our meter only registers noise levels above 40 decibels, and most of the field is quieter than that at idle.

The Silencer and PRO82+ both prove inaudible to our sound level meter at idle, and the ES-800 isn't far off the meter's 40-decibel threshold. The PSUs from Zalman and OCZ do well here, too, while the ePower Thunder is more than two decibels louder than anything else.

Even with its old-school 80mm fan, the Silencer is still more than a decibel quieter than its closest rival under load. Zalman and BFG share second place here, followed very closely by Enermax's PRO82+. At the louder end of the spectrum, ePower and Thermaltake swap places, with the latter generating the highest noise levels of the lot.

Power consumption
Power consumption was measured at the wall socket for the entire system, sans monitor or speakers.

There's a 9-watt spread in our idle power consumption results, with the ES-800 taking top honors ahead of units from Enermax and Zalman. OCZ and Thermaltake fare the worst here. The EliteXStream's result is particularly disappointing in light of its strong performance elsewhere.

Under load, the field splits into two packs. The three front-runners are led by Zalman's ZM-750HP, and they have a healthy lead over the rest of the field. ePower's Thunder proves to be the least efficient under load, pulling 30 more watts than the ZM-750HP.