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Asus ROG Strix 750W Power Supply Review

The strongest assets of the Asus ROG Strix 750W are the high performance and the silent operation, along with the good build quality.

Asus ROG Strix 750W
(Image: © Asus)

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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(Image credit: Tom's Hardware)

Results 1-8: Load Regulation

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The load regulation is extra tight on all rails but 5VSB, where it is just satisfactory. 

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

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The hold-up time is close to 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

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The inrush current is quite high with 230V, and at normal levels with 115V input. 

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.

Test #12V5V3.3V5VSBDC/AC (Watts)EfficiencyFan Speed (RPM)PSU Noise (dB[A])Temps (In/Out)PF/AC Volts
14.414A1.999A1.986A0.984A74.95385.554%0<6.0 44.89°C0.925
12.087V4.999V3.327V5.082V87.609 40.38°C115.09V
29.855A3.000A2.977A1.184A150.00689.178%0<6.0 45.67°C0.954
12.087V4.996V3.325V5.069V168.210 40.68°C115.09V
315.632A3.504A3.475A1.384A225.00890.311%0<6.0 46.28°C0.969
12.088V4.994V3.324V5.057V249.149 40.76°C115.09V
421.413A4.004A3.972A1.586A300.01690.252%4789.8 41.19°C0.977
12.087V4.995V3.322V5.045V332.421 47.35°C115.09V
526.810A5.007A4.971A1.788A374.48290.004%82024.7 42.18°C0.981
12.084V4.994V3.320V5.034V416.071 49.13°C115.09V
632.245A6.011A5.967A1.992A449.42289.591%82924.9 42.49°C0.983
12.083V4.992V3.318V5.020V501.640 50.36°C115.09V
737.708A7.017A6.968A2.197A524.74089.120%84025.2 43.20°C0.986
12.083V4.989V3.316V5.007V588.799 52.07°C115.09V
843.167A8.003A7.965A2.404A599.94088.555%85725.6 44.05°C0.987
12.084V4.987V3.314V4.993V677.475 53.35°C115.09V
948.996A8.526A8.454A2.408A674.57587.881%110032.7 44.37°C0.989
12.084V4.985V3.312V4.986V767.603 54.62°C115.09V
1054.639A9.030A8.970A3.023A749.79387.071%148740.4 45.55°C0.990
12.081V4.984V3.310V4.963V861.130 56.59°C115.08V
1160.876A9.032A8.976A3.027A825.02286.257%194547.1 46.84°C0.990
12.079V4.982V3.309V4.956V956.474 58.64°C115.08V
CL10.102A12.000A11.998A0.000A100.90084.017%605 16.1 42.54°C0.943
12.100V4.987V3.319V5.086V120.095 50.10°C115.11V
CL262.010A1.000A1.000A1.000A762.28687.484%1553 41.3 45.01°C0.990
12.078V4.993V3.317V5.020V871.341 55.78°C115.09V

The power supply has high tolerance in increased operating temperatures, and the efficiency levels are satisfactory. Even at such high temperatures, the PSU meets the 80 PLUS Gold 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.

Test #12V5V3.3V5VSBDC/AC (Watts)EfficiencyFan Speed (RPM)PSU Noise (dB[A])PF/AC Volts
11.229A0.499A0.493A0.196A19.98269.437%0<6.00.840
12.074V5.008V3.333V5.108V28.777115.08V
22.456A0.999A0.993A0.392A39.97079.867%0<6.00.895
12.080V5.001V3.329V5.101V50.046115.09V
33.688A1.499A1.487A0.589A60.00284.053%0<6.00.918
12.081V5.001V3.329V5.094V71.386115.09V
44.912A2.000A1.983A0.786A79.95286.472%0<6.00.926
12.084V4.999V3.328V5.087V92.460115.09V

With 20% and 40% load, it would be nice to see higher than 70% and 80% efficiency levels, respectively.

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.

Test #12V5V3.3V5VSBDC/AC (Watts)EfficiencyFan Speed (RPM)PSU Noise (dB[A])PF/AC Volts
11.079A0.210A0.210A0.052A15.03663.507%0<6.00.818
12.063V5.013V3.334V5.113V23.676115.08V

The unit cannot pass the 70% mark, with 2% of its max-rated-load and this means that it doesn't meet the corresponding ATX requirement which will be in effect 

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

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The overall efficiency at normal loads is satisfactory, although lower than what the majority of the competition achieves, while with light loads is high enough. The problem is with a 2% load, where the PSU cannot reach the 70% mark.

5VSB Efficiency

Test #5VSBDC/AC (Watts)EfficiencyPF/AC Volts
10.100A0.51172.585%0.111
5.112V0.704115.12V
20.250A1.27875.666%0.223
5.109V1.689115.12V
30.550A2.80777.094%0.334
5.103V3.641115.12V
41.000A5.09377.015%0.402
5.093V6.613115.12V
51.500A7.62277.044%0.438
5.081V9.893115.12V
63.000A15.12675.728%0.488
5.042V19.974115.11V
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Results 19-20: 5VSB Efficiency

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The 5VSB circuit needs an upgrade, for increased efficiency. 

Power Consumption In Idle And Standby

Mode12V5V3.3V5VSBWattsPF/AC Volts
Idle12.046V5.017V3.333V5.118V8.9850.595
115.1V
Standby0.0570.009
115.1V
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Results 21-22: Vampire Power

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The PSU consumes low energy levels at standby.

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 highly relaxed, even at high operating temperatures that exceed 40 degrees Celsius. 

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 semi-passive operation doesn't last long, but the fan's speeds remain low in all cases, and so does the noise output.

MORE: Best Power Supplies

MORE: How We Test Power Supplies

MORE: All Power Supply Content

  • octavecode
    I was about to say "looks a lot like a Seasonic unit" then i checked the manufacturer. :P
    Best PSU reviewer , greetings from Greece.
    Stay strong and healthy everybody.
    Reply
  • Aris_Mp
    octavecode said:
    I was about to say "looks a lot like a Seasonic unit" then i checked the manufacturer. :p
    Best PSU reviewer , greetings from Greece.
    Stay strong and healthy everybody.

    Thank you for your kind words!
    Reply
  • karthyks
    Not sure if I got a faulty unit. I built a PC with Ryzen 3900x and Gigabyte Rtx 2080 Super along with this PSU. And it failed me after 3 days. My PC shuts down whenever I login to windows and randomly when I open a exe file. After swapping new motherboard, new Ram, new graphics card, i found the problem is with PSU. And I use thermaltake 850W 80+ and now everything is good so far.
    Reply