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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)

Advanced Transient Response Tests

For details about our transient response testing, please click here.

In the real world, power supplies are always working with loads that change. It's of immense importance, then, for the PSU to keep its rails within the ATX specification's defined ranges. The smaller the deviations, the more stable your PC will be with less stress applied to its components. 

We should note that the ATX spec requires capacitive loading during the transient rests, but in our methodology, we also choose to apply a worst case scenario with no additional capacitance on the rails. 

Advanced Transient Response at 20% – 200ms

VoltageBeforeAfterChangePass/Fail
12V12.085V11.998V0.72%Pass
5V4.996V4.903V1.86%Pass
3.3V3.325V3.195V3.91%Pass
5VSB5.069V5.013V1.10%Pass

Advanced Transient Response at 20% – 20ms

VoltageBeforeAfterChangePass/Fail
12V12.085V11.958V1.05%Pass
5V4.996V4.884V2.24%Pass
3.3V3.325V3.169V4.69%Pass
5VSB5.069V5.018V1.01%Pass

Advanced Transient Response at 20% – 1ms

VoltageBeforeAfterChangePass/Fail
12V12.085V11.975V0.91%Pass
5V4.996V4.885V2.22%Pass
3.3V3.325V3.165V4.81%Pass
5VSB5.069V5.019V0.99%Pass

Advanced Transient Response at 50% – 200ms

VoltageBeforeAfterChangePass/Fail
12V12.078V12.003V0.62%Pass
5V4.991V4.892V1.98%Pass
3.3V3.319V3.182V4.13%Pass
5VSB5.035V4.977V1.15%Pass

Advanced Transient Response at 50% – 20ms

VoltageBeforeAfterChangePass/Fail
12V12.077V11.952V1.04%Pass
5V4.991V4.875V2.32%Pass
3.3V3.319V3.157V4.88%Pass
5VSB5.035V5.000V0.70%Pass

Advanced Transient Response at 50% – 1ms

VoltageBeforeAfterChangePass/Fail
12V12.077V11.967V0.91%Pass
5V4.991V4.875V2.32%Pass
3.3V3.320V3.156V4.94%Pass
5VSB5.034V4.986V0.95%Pass
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(Image credit: Tom's Hardware)

Results 25-29: Transient Response

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The transient response of the +12V rail, which is the most important, is excellent, and the same goes for 5VSB. The 5V rail has satisfactory performance, while there is room for improvement at 3.3V, where the voltage level dropped below 3.2V, in all tests.

Turn-On Transient Tests

In the next set of tests, we measure the PSU's response in simpler transient load scenarios—during its power-on phase. Ideally, we don't want to see any voltage overshoots or spikes since those put a lot of stress on the DC-DC converters of installed components.

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(Image credit: Tom's Hardware)

Turn-On Transient Response Scope Shots

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Typically for a Seasonic Focus-based platform, the +12V rail requires some time till it reaches the nominal voltage. There is nothing to worry about, though.

Power Supply Timing Tests

There are several signals generated by the power supply, which need to be within specified, by the ATX spec, ranges. If they are not, there can be compatibility issues with other system parts, especially mainboards. From year 2020, the PSU's Power-on time (T1) has to be lower than 150ms and the PWR_OK delay (T3) from 100 to 150ms.

PSU Timings Table
T1 (Power-on time) & T3 (PWR_OK delay)
LoadT1T3
20%82ms318ms
50%100ms318ms

The PWR_OK delay is out of the 100-150ms region, so the PSU does not support the alternative sleep mode, which is a requirement by the newest ATX spec.

Ripple Measurements

Ripple represent the AC fluctuations (periodic) and noise (random) found in the PSU's DC rails. This phenomenon significantly decreases the capacitors' lifespan because it causes them to run hotter. A 10-degree Celsius increase can cut into a cap's useful life by 50%. Ripple also plays an important role in overall system stability, especially when overclocking is involved.

The ripple limits, according to the ATX specification, are 120mV (+12V) and 50mV (5V, 3.3V, and 5VSB).

Test12V5V3.3V5VSBPass/Fail
10% Load11.8 mV8.6 mV12.7 mV6.1 mVPass
20% Load15.4 mV9.6 mV14.7 mV6.2 mVPass
30% Load17.3 mV10.4 mV16.0 mV6.8 mVPass
40% Load19.5 mV11.6 mV18.2 mV7.5 mVPass
50% Load19.9 mV11.2 mV19.8 mV7.8 mVPass
60% Load16.9 mV11.1 mV22.0 mV9.4 mVPass
70% Load15.9 mV11.5 mV22.5 mV10.4 mVPass
80% Load16.5 mV11.5 mV17.5 mV11.4 mVPass
90% Load17.9 mV11.8 mV17.9 mV13.0 mVPass
100% Load29.1 mV12.8 mV20.3 mV14.2 mVPass
110% Load32.3 mV12.9 mV22.3 mV14.4 mVPass
Crossload 118.6 mV11.5 mV19.1 mV6.8 mVPass
Crossload 228.5 mV10.8 mV20.0 mV12.3 mVPass
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Results 30-33: Ripple Suppression

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The ripple at +12V with full load increases significantly, still it remains below 30mV. All in all, the ripple suppression is good on all rails, but nowhere close to the amazing levels that the Corsair RM750x model achieves, thanks to the good design and the in-cable caps.

Ripple At Full Load

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Ripple Full Load Scope Shots

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Ripple At 110% Load

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Ripple 110% Load Scope Shots

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Ripple At Cross-Load 1

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Ripple CL1 Load Scope Shots

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Ripple At Cross-Load 2

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Ripple CL2 Load Scope Shots

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EMC Pre-Compliance Testing – Average & Quasi-Peak EMI Detector Results

Electromagnetic Compatibility (EMC) is the ability of a device to operate properly in its environment without disrupting the proper operation of other nearby devices.

Electromagnetic Interference (EMI) stands for the electromagnetic energy a device emits, and it can cause problems in other nearby devices if too high. For example, it can be the cause of increased static noise in your headphones or/and speakers.

(Image credit: Tom's Hardware)

Two high spurs exceed the limits with the average and the QP detectors, at 342KHz and 581KHz, respectively.

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