Test Setup

Primary Rails Load Regulation

The following charts show the voltage values of the main rails, recorded over a range from 60 W to the maximum specified load, and the deviation (in percent) for the same load range. Tight load regulation is an important characteristic for every power supply since it allows for constant voltage levels despite changes in load.

5VSB Regulation

Hold-up Time

Hold-up time represents the amount of time, usually measured in milliseconds, a PSU can maintain output regulations as defined by the ATX specification without input power. Hold-up time is the amount of time the system can continue to run without shutting down or rebooting during a power interruption. In the following screenshots, the blue line is the mains signal and the green line is the "Power Good" signal, while the yellow line represents the +12V rail.

Inrush Current

Inrush current, or switch-on surge, refers to the maximum instantaneous input current drawn by an electrical device when it is first turned on. Large enough inrush current can cause the tripping of circuit breakers and fuses and may also damage switches, relays, and bridge rectifiers. As a result, the lower the inrush current of a PSU right as it is turned on, the better.

10-110% Load Testing

These tests reveal the PSU's load regulation and efficiency levels at high ambient temperatures. They also show how the fan-speed profile behaves under tough operating conditions.

Light Load Testing

In the following tests, we measure the PSU's efficiency at loads significantly lower than 10 percent of its maximum capacity (the lowest load the 80 PLUS standard measures). This is important for when a PC is idle with its power-saving features turned on.

Ultra-Light Load Testing

The applied load in this test is only 10 W for PSUs with 500 W and lower capacities. We dial in 2% of the maximum-rated-capacity with stronger PSUs. This test is only run with 115 V input.


The efficiency results with 2%, of the maximum-rated-capacity load are disappointing.

Efficiency

Using the results that we gathered so far, we plotted a chart showing the PSU's efficiency at low loads and loads ranging from 10 to 110 percent of the maximum-rated capacity.



Efficiency levels are high in both load ranges (40–100 W and 20%–100%), which is not the case with 2% of the maximum-rated-capacity load. Starting in July 2020, The ATX specification will require PSUs to produce more than 70% efficiency in this area.

5VSB Efficiency

Efficiency levels at 5VSB are low.

Power Consumption in Idle and Standby

Fan RPM, Delta Temperature and Output Noise

The following results were obtained at 37–47 °C ambient.





The following results were obtained at 30–32 °C ambient.