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Transient Response Tests, Ripple Measurements and EMC Pre-Compliance Testing

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

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Voltage	Before	After	Change	Pass/Fail
12V	12.103V	11.971V	1.09%	Pass
5V	5.026V	4.898V	2.55%	Pass
3.3V	3.371V	3.228V	4.24%	Pass
5VSB	5.072V	5.017V	1.08%	Pass

Advanced Transient Response at 20% – 20ms

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Voltage	Before	After	Change	Pass/Fail
12V	12.104V	11.926V	1.47%	Pass
5V	5.024V	4.874V	2.99%	Pass
3.3V	3.372V	3.206V	4.92%	Pass
5VSB	5.073V	5.025V	0.95%	Pass

Advanced Transient Response at 20% – 1ms

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Voltage	Before	After	Change	Pass/Fail
12V	12.106V	11.885V	1.83%	Pass
5V	5.025V	4.879V	2.91%	Pass
3.3V	3.371V	3.185V	5.52%	Pass
5VSB	5.074V	5.021V	1.04%	Pass

Advanced Transient Response at 50% – 200ms

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Voltage	Before	After	Change	Pass/Fail
12V	12.077V	11.962V	0.95%	Pass
5V	5.018V	4.883V	2.69%	Pass
3.3V	3.364V	3.213V	4.49%	Pass
5VSB	5.036V	4.980V	1.11%	Pass

Advanced Transient Response at 50% – 20ms

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Voltage	Before	After	Change	Pass/Fail
12V	12.079V	11.930V	1.23%	Pass
5V	5.019V	4.862V	3.13%	Pass
3.3V	3.364V	3.191V	5.14%	Pass
5VSB	5.037V	4.984V	1.05%	Pass

Advanced Transient Response at 50% – 1ms

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Voltage	Before	After	Change	Pass/Fail
12V	12.080V	11.925V	1.28%	Pass
5V	5.019V	4.865V	3.07%	Pass
3.3V	3.363V	3.154V	6.21%	Pass
5VSB	5.038V	4.981V	1.13%	Pass

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(Image credit: Tom's Hardware)

Results 25-29: Transient Response

The transient response at +12V is satisfactory, but the competing offerings perform better. The situation remains the same, with the other rails.

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

The performance is good here. The only things we notice are a tiny spike at 5VSB and a small step in the "PSU OFF to Full 12V" test.

Ripple Measurements

Ripple represents 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).

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Test	12V	5V	3.3V	5VSB	Pass/Fail
10% Load	7.1 mV	6.7 mV	14.0 mV	8.0 mV	Pass
20% Load	7.4 mV	8.9 mV	15.0 mV	8.6 mV	Pass
30% Load	8.7 mV	12.7 mV	18.0 mV	9.6 mV	Pass
40% Load	10.7 mV	9.7 mV	18.7 mV	10.7 mV	Pass
50% Load	20.0 mV	10.6 mV	19.0 mV	12.2 mV	Pass
60% Load	15.0 mV	12.1 mV	20.4 mV	13.5 mV	Pass
70% Load	18.4 mV	13.0 mV	23.0 mV	14.4 mV	Pass
80% Load	21.4 mV	15.1 mV	24.1 mV	17.0 mV	Pass
90% Load	24.5 mV	14.8 mV	27.5 mV	17.3 mV	Pass
100% Load	36.7 mV	16.2 mV	29.8 mV	20.8 mV	Pass
110% Load	32.5 mV	15.6 mV	28.2 mV	20.0 mV	Pass
Crossload 1	12.1 mV	14.8 mV	20.2 mV	12.5 mV	Pass
Crossload 2	33.6 mV	15.2 mV	27.0 mV	18.2 mV	Pass

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(Image credit: Tom's Hardware)

Results 30-33: Ripple Suppression

Strangely enough, the ripple suppression at +12V with 110% load is a little better than with full load, at the same operating temperature. This is something that we don't see every day.

The ripple suppression is satisfactory at +12V since it stays below 40mV. On the 5V and 5VSB rails, ripple is low, while we would like to see a little lower readings at 3.3V.

Ripple At Full Load

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(Image credit: Tom's Hardware)

Ripple Full Load Scope Shots

Ripple At 110% Load

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(Image credit: Tom's Hardware)

Ripple 110% Load Scope Shots

Ripple At Cross-Load 1

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(Image credit: Tom's Hardware)

Ripple CL1 Load Scope Shots

Ripple At Cross-Load 2

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(Image credit: Tom's Hardware)

Ripple CL2 Load Scope Shots

EMC Pre-Compliance Testing – Average & 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 close-by devices.

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