Asus ROG Strix 650W Power Supply Review

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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Results 1-8: Load Regulation

The load regulation is tight on the +12V, 5V and 3.3V rails and within 3% at 5VSB.

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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Results 9-12: Hold-Up Time

The hold-up time is longer than 20ms, 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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Results 13-14: Inrush Current

The registered inrush currents are at normal levels. 

10-110% Load Tests

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

The power supply can handle high operating temperatures, which exceed 45 degrees Celsius. Moreover, despite the harsh conditions, the PSU is very close to the 80 PLUS Gold efficiency requirements. 

20-80W Load Tests

In the following tests, we measure the PSU'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.

It would be nice to see higher than 70% efficiency with 20W load. In the other three tests, the efficiency levels exceed the 80% mark.

2% or 10W Load Test

Intel plans on raising the ante at efficiency levels under ultra-light loads. So from July 2020, the ATX spec will require 70% and higher efficiency with 115V input. The applied load is only 10W for PSUs with 500W and lower capacities, while for stronger units we dial 2% of their max-rated-capacity.

The PSU cannot reach (or exceed) 70% efficiency with 2% of its max-rated-capacity load. This means that it won't meet the upcoming, in a few months, ATX spec requirement. 

Efficiency

Next, we plotted a chart showing the PSU'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 and lower electricity bills.

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Results 15-18: Efficiency

Compared to products with similar specifications, the efficiency at normal and light loads is at average levels, while with super-light loads, it is quite low. 

5VSB Efficiency

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Results 19-20: 5VSB Efficiency

The 5VSB rail's efficiency is low. 

Power Consumption In Idle And Standby

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Results 21-22: Vampire Power

The vampire power levels are quite low. 

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 quite loose, even at high operating temperatures. This is possible thanks to the large heat sinks, which effectively handle the (not so high) thermal loads.

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

The fan profile doesn't last long, and even in the worst-case scenario, the fan's noise remains below 30 dB(A). 

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