For testing a power supply we have two different approaches. The first is the simple test of sound measurement. Some people are quite particular as to the amount of sound their PC and connected peripherals produce. Other could care less. The second test is voltage measurements.

Sound Testing

For sound testing we use our Omega HHSL1 sound meter. Measuring in dbA we can make an accurate determination of the audible noise level of a particular power supply or fan or what ever we would choose to measure. We try to find the quietest atmosphere possible for our measurements, and it just so happens that on of my bathrooms at home gets down to 30 dbA or less in the middle of the night (providing there is no rain outside or snoring dog inside). The measurements are taken from a distance of 10 centimeters, then 1 meter, and finally at 2 meters. The ambient noise level is also taken for comparison purposes. One more note; when preforming sound testing I always rest a power supply, fan, or cooler on a towel. I do this as any vibrations from the part can travel through the counter top and become amplified by the wooden cabinet below. It is also important to keep to microphone pickup of the sound meter out of the exhaust flow of the exhaust fan to eliminate the possibility of false wind noise. Finally, if I can take measurements with the sound meter resting on a table top, I will. My own pulse and respiration is enough to have the sound meter register a reading.

So with out further adieu, our sound measurements.

I think these figures speak for themselves. The e-Power 1KW supply is pretty quiet across the range of measured distances. But if you noticed that the sound level of other power supplies drops of far more significantly in relation to distance, that has to do with the type of sound the e-Power 1KW is putting out. Because of the ball bearing fan design, there is far more bass. Low frequency bass will travel farther with less fade. Higher pitched treble doesn't travel as far and dissipated quickly. Of course, when any power supply is tossed inside a case and gaming gun fire rings aloud, you probably won't even notice the hum of your power supply.

Load Testing

Load testing is a slightly different beast, the purpose behind being the difference in voltage on the different rails between idle and load. If there is a considerable difference between idle and load, than said power supply might not preform to spec properly. If the difference is voltages is negligible, then the supply is strong.

To measuring the three voltage rail we'll be using out Mastercraft 052-0060-2 volt meter. For testing in this case we measure the 3.3V, the 5V, and the 12V rails at idle and load. Idle would be when we're at the Windows desktop and all is calm. Load entails running two instances of CPU burn-in with the HDR snow scene in 3DMark2006 at the same time. All this while running a couple of ATI CrossFire cards to chug some serious wattage. Our base test system for power supplies is also our standard video card test bench system.