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, the green line the "Power Good" signal, and the yellow line the +12V rail.







Hold-up time is longer than 20 ms, and the power-ok signal is accurate. There is nothing more to ask for here.

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.



Inrush current is high, but not at dangerously so.

10-110% Load Testing

These tests reveal the SF-850F14RG's load regulation and efficiency levels under high ambient temperatures. They also show how the fan-speed profile behaves in tough operating conditions.


Load regulation is satisfactory on all rails, and as semi-passive mode lasts for quite a while under even high operating temperatures, a relaxed fan profile is used. However, the power factor readings are not that high. I expected closer to unity readings at high loads. With that said, the PSU doesn't have a problem operating in harsh conditions as efficiency levels do not take a significant hit. While registered efficiency levels in these tests should still be a bit higher to truly be competitive, they go to show that the platform can handle the load without difficulty.

Light Load Testing

In the following tests, we measure the SF-850F14RG'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 its power-saving features turned on.


Efficiency levels at light loads are high, but the PF readings are low.

Ultra-Light Load Testing

The applied load in this test is only 10 W for PSUs with 500 W and less capacity. For stronger units, we dial in 2% of the maximum-rated capacity. We only run this test with 115 V input.


The PSU achieves over 70% efficiency with 2% of its maximum-rated-capacity load, which has it meet a major requirement of the newest ATX specification.

Efficiency

Using the results we gathered so far, we plotted a chart showing the SF-850F14RG's efficiency at low loads and loads ranging from 10 to 110 percent of its maximum-rated capacity.



Efficiency levels are high at light loads, but other models with similar specifications outperform it with regular loads.

5VSB Efficiency

The 5VSB rail is very efficient in all the tests I conducted.

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.