Asus ROG Strix 650W Power Supply Review

The Asus ROG Strix 650W is a strong but costly power supply.

Asus ROG Strix 650W
(Image credit: © Asus)

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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.

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

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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.

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.

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.

Swipe to scroll horizontally
Test # 12V 5V 3.3V 5VSB DC/AC (Watts) Efficiency Fan Speed (RPM) PSU Noise (dB[A]) Temps (In/Out) PF/AC Volts
1 3.583A 1.999A 1.989A 0.980A 65.022 84.513% 0 <6.0 45.07°C 0.951
12.116V 5.006V 3.318V 5.106V 76.937 39.34°C 115.18V
2 8.137A 3.002A 2.987A 1.178A 129.511 88.832% 0 <6.0 46.60°C 0.977
12.117V 5.001V 3.315V 5.093V 145.794 40.53°C 115.18V
3 13.088A 3.504A 3.473A 1.378A 194.639 89.971% 331 7.6 40.97°C 0.986
12.120V 4.997V 3.312V 5.080V 216.336 47.45°C 115.18V
4 18.041A 4.005A 3.988A 1.579A 259.865 90.109% 813 24.6 41.38°C 0.988
12.120V 4.995V 3.310V 5.068V 288.389 48.30°C 115.18V
5 22.665A 5.009A 4.990A 1.781A 325.164 89.909% 684 19.6 42.23°C 0.990
12.118V 4.992V 3.307V 5.055V 361.659 49.54°C 115.17V
6 27.225A 6.018A 5.994A 1.984A 389.684 89.481% 852 25.5 42.76°C 0.991
12.116V 4.988V 3.304V 5.042V 435.492 50.62°C 115.17V
7 31.848A 7.025A 6.999A 2.189A 454.998 88.928% 862 25.8 43.48°C 0.991
12.116V 4.985V 3.301V 5.027V 511.645 52.08°C 115.17V
8 36.469A 8.034A 8.005A 2.394A 520.308 88.363% 891 26.6 43.67°C 0.992
12.117V 4.980V 3.298V 5.014V 588.833 53.20°C 115.17V
9 41.492A 8.544A 8.499A 2.398A 585.237 87.722% 1157 33.6 44.23°C 0.992
12.116V 4.976V 3.295V 5.005V 667.147 54.40°C 115.17V
10 46.258A 9.055A 9.024A 3.011A 650.084 86.964% 1459 40.1 45.82°C 0.993
12.114V 4.971V 3.291V 4.983V 747.529 56.73°C 115.17V
11 51.618A 9.064A 9.036A 3.016A 714.922 86.257% 1784 45.3 46.60°C 0.993
12.112V 4.967V 3.287V 4.974V 828.832 58.28°C 115.17V
CL1 0.158A 12.002A 12.001A 0.000A 101.506 84.522% 366 8.5 42.55°C 0.972
12.131V 4.993V 3.305V 5.103V 120.094 49.90°C 115.19V
CL2 54.024A 1.003A 1.001A 1.000A 667.674 87.431% 1562 41.6 46.07°C 0.993
12.112V 4.978V 3.297V 5.042V 763.658 57.03°C 115.17V

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.

Swipe to scroll horizontally
Test # 12V 5V 3.3V 5VSB DC/AC (Watts) Efficiency Fan Speed (RPM) PSU Noise (dB[A]) PF/AC Volts
1 1.209A 0.501A 0.480A 0.195A 19.747 69.854% 0 <6.0 0.787
12.106V 5.016V 3.326V 5.131V 28.269 115.18V
2 2.460A 1.000A 0.994A 0.391A 40.098 80.381% 0 <6.0 0.907
12.108V 5.009V 3.321V 5.124V 49.885 115.18V
3 3.651A 1.499A 1.477A 0.587A 59.627 84.391% 0 <6.0 0.945
12.110V 5.008V 3.320V 5.116V 70.656 115.18V
4 4.904A 2.000A 1.989A 0.783A 80.013 86.680% 0 <6.0 0.963
12.113V 5.006V 3.318V 5.109V 92.309 115.18V

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.

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Test # 12V 5V 3.3V 5VSB DC/AC (Watts) Efficiency Fan Speed (RPM) PSU Noise (dB[A]) PF/AC Volts
1 0.933A 0.208A 0.203A 0.051A 13.267 61.197% 0 <6.0 0.698
12.096V 5.020V 3.329V 5.136V 21.679 115.18V

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.

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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Test # 5VSB DC/AC (Watts) Efficiency PF/AC Volts
1 0.100A 0.514 72.191% 0.110
5.136V 0.712 115.17V
2 0.250A 1.284 75.485% 0.221
5.133V 1.701 115.17V
3 0.550A 2.820 76.672% 0.334
5.126V 3.678 115.17V
4 1.000A 5.118 77.125% 0.403
5.116V 6.636 115.17V
5 1.500A 7.660 76.954% 0.438
5.105V 9.954 115.16V
6 3.000A 15.209 75.303% 0.483
5.069V 20.197 115.16V

The 5VSB rail's efficiency is low. 

Power Consumption In Idle And Standby

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Mode 12V 5V 3.3V 5VSB Watts PF/AC Volts
Idle 12.089V 5.023V 3.331V 5.138V 7.791 0.553
115.2V
Standby 0.056 0.009
115.2V

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).

(Image credit: Tom's Hardware)

(Image credit: Tom's Hardware)

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.       

(Image credit: Tom's Hardware)

(Image credit: Tom's Hardware)

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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Aris Mpitziopoulos
Contributing Editor

Aris Mpitziopoulos is a contributing editor at Tom's Hardware, covering PSUs.