Corsair RM650 Power Supply Review: Silent and Efficient

Load Regulation, Hold-Up Time, Inrush Current, Efficiency and Noise

To learn more about our PSU tests and methodology, please check out How We Test Power Supply Units. 

Primary Rails And 5VSB Load Regulation

The following charts show the main rails' voltage values recorded between a range of 40W up to the PSU's maximum specified load, along with the deviation (in percent). Tight regulation is an important consideration every time we review a power supply because it facilitates constant voltage levels despite varying loads. Tight load regulation also, among other factors, improves the system’s stability, especially under overclocked conditions and, at the same time, it applies less stress to the DC-DC converters that many system components utilize.

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The load regulation is tight, on all rails.

Hold-Up Time

Put simply; hold-up time is the amount of time that the system can continue to run without shutting down or rebooting during a power interruption.

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The hold-up time is longer than 17ms, which is what the ATX spec requires, and the power ok signal is accurate.

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 circuit breakers and fuses to trip. It can 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.

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Low inrush currents, with both voltage inputs.

10-110% Load Tests

These tests reveal the RM650’s load regulation and efficiency levels under high ambient temperatures. They also show how the fan speed profile behaves under increased operating temperatures.

The unit's passive operation lasts up to the third test, with close to 41°C ambient. We have to increase the load at 110% and crank up the heat inside the hot box, at higher than 46°C, to force the fan to operate at its full speed.

20-80W Load Tests

In the following tests, we measure the RM650's efficiency at loads significantly lower than 10% 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.

The efficiency levels under light loads are extremely high.

Efficiency

Next, we plotted a chart showing the RM650’s efficiency at low loads, and loads from 10 to 110% of its maximum-rated capacity. The higher a PSU’s efficiency, the less energy goes wasted, leading to a reduced carbon footprint, besides lower electricity bills.

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The RM650 is efficient under both light and normal loads.

5VSB Efficiency

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The 5VSB rail is strong and efficient enough to meet the competition.

Power Consumption In Idle And Standby

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Fan RPM, Delta Temperature, And Output Noise

All results are obtained between an ambient temperature of 37 to 47 degrees Celsius (98.6 to 116.6 degrees Fahrenheit).

The fan profile is relaxed and the semi-passive operation offers minimized noise output at loads up to around 200W, even at high ambient temperatures. As you will see in the graph below, the fan's passive operation won't last long only if you apply high loads on the minor rails.

The following results were obtained at 30 to 32 degrees Celsius (86 to 89.6 degrees Fahrenheit) ambient temperature.       

We are used to seeing ultra short semi-passive operation periods at CWT platforms, under high loads on the minor rails. Apparently the DC-DC converters that generate the 5V and 3.3V rails heavily rely on airflow, because they lack the necessary heat sinks.

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