Testing – DC Output Voltage Load Regulation

To simulate real world operation, each power supply was connected to the load tester, supplied with 115 VAC, and allowed to burn-in for 24 hrs before voltage readings were taken.  In this test we are interested in seeing how well a PSU can maintain the various output voltages while under a moderately heavy load.  The DC output voltages were measured with a FLUKE digital multimeter at the ATX connector. 

The ATX tolerance for voltages states how much each output (rail) is allowed to fluctuate.  Seasonic specifies ±5% for all outputs except for the -12 V output, which is ±10%.

Three Seasonic ATX Power Supplies Reviewed - Cases and Cooling 61

The following table lists the DC voltage regulation results for the three Seasonic PSUs.

Three Seasonic ATX Power Supplies Reviewed - Cases and Cooling 62

As you can see, all of the DC outputs were held well within the ATX specification while operating under a 240 watt combined load.  The Super Silencer 350 exhibited the best regulation while the larger 460 had the lowest values, especially on the +3.3 VDC rail, but still within spec.  All three units produced -12 VDC outputs near the maximum limit (-13.20 VDC) with no load applied.  Placing a slight load across the -12 VDC outputs (56 ohm resistor) brought the voltages down closer to their nominal values.

Of particular interest are the three main power rails (+3.3V, +5V and +12V) and the 5VSB line.  Maintaining these outputs at optimum levels is important to the reliable operation of any PC.  If you push components (overclock/over-volt) then they become even more critical.



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