The PSU passed the full-load test (at 380W) easily.
Together with an APC SmartUPS SC 620 this power supply worked at loads up to 343W (from the mains) and 335W (from the battery). The UPS switched to the battery without problems.
The output voltage ripple is within the normal limits at full load.
The cross-load diagram looks good. The +5 voltage sags somewhat while the +12V voltage increases when there is a high load on the +5V rail. However, even the configuration with four WD Raptor drives I performed my tests with and whose power consumption I measured precisely consumes but little power from the +5V rail. In every test mode (marked with crosses in the cross-load diagram) the PSU’s voltages are within the “green zone”. And you can also see that the PSU has a double reserve of power for my “reference” configuration.
The PSU fan works at a constant speed until a load of 250W and then accelerates. The PSU is very quiet. It is in fact inaudible at low loads. You can only hear it at loads higher than 300W but my configuration doesn’t reach that level notwithstanding the advanced graphics card and CPU.
I perform the fan speed measurements when the PSU is taken out of the system case, i.e. at room temperature. As a rule, the temperature of the incoming air is going to be somewhat higher in a closed system case and the PSU fan begins to accelerate at a lower load. This rule doesn’t apply to the NSK3480, though. This system case has a partition that separates it into two volumes and the air around the PSU is not heated up by the CPU or the graphics card.
The efficiency is 85-86% across a wide range of loads, which is a good result. I perform the test in a 220V power grid but the PSU can work easily (without a manual switch) in a 110V grid as well thanks to its active PFC. Its efficiency is going to be 2-3% lower in a 110V power grid.
So, I can see no fault with the EarthWatts EA-380. It is stable and quiet. And it offers enough wattage and connectors to build as advanced a gaming configuration in the microATX system case it comes with as microATX mainboards permit.