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 the load.

5VSB Regulation

Hold-up Time

Hold-up time represents the amount of time, usually measured in milliseconds, that a PSU can maintain output regulations as defined by the ATX specification without input power. hold-up time is the amount of time that 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, the green line is the "Power Good" signal, and the yellow line represents the +12V rail.







Hold-up time is over 17 ms, but the power_ok signal's hold-up time is lower than 16 ms.

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. A 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 HG2-850's load regulation and efficiency levels under high ambient temperatures. They also show how the fan speed profile behaves under tough operating conditions.


Load regulation could be tighter at +12V and 3.3V, and the fan's noise output is very high at high operating temperatures and increased loads. Although the PSU is efficient enough, FSP's engineers chose an aggressive fan-speed profile, which doesn't make much sense. I get that the fan's diameter is small, so it has to spin at high speeds to offer decent airflow, but close to 3,000 RPM is overkill for an ETA-A and 80 PLUS Gold certified PSU.

Light Load Testing

In the following tests, we measure the HG2-850'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 representing when a PC is idle, with 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, while we dial in 2% of the maximum-rated-capacity for stronger PSUs. We only run this test with 115 V input.


Efficiency with 2% of the maximum-rated-output load is over 60%, but if everything goes according to plan, Intel will increase the limit to 70% in July 2020.

Efficiency

Using the results we gathered so far, we plotted a chart showing the HG2-850's efficiency at low loads, and loads from 10 to 110 percent of its maximum-rated capacity.


Under light loads, the HG2-850 roughly places in the middle of the pack, and close to its competitors with normal loads.

5VSB Efficiency

There might not be any 80% readings, but most of them are above 70%. Even with 0.1 A load at 5VSB, the PSU achieves >60% efficiency. With 115 V input, efficiency levels at 5VSB are notably higher.

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.





I chose not to engage the semi-passive operation in these tests since it doesn't stay active for long anyway. The difference in overall noise output is negligible, and the good thing is that the fan starts at a low 700 –725 RPM.