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Transient Response Tests, Ripple Measurements & EMC Pre-Compliance Testing
Advanced Transient Response Tests
For details on 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 chose to apply the worst case scenario with no extra capacitance on the rails.
Advanced Transient Response at 20 Percent – 200ms
| Voltage | Before | After | Change | Pass/Fail |
|---|---|---|---|---|
| 12V | 12.105V | 11.958V | 1.21% | Pass |
| 5V | 5.058V | 4.915V | 2.83% | Pass |
| 3.3V | 3.344V | 3.196V | 4.43% | Pass |
| 5VSB | 5.041V | 4.979V | 1.23% | Pass |
Advanced Transient Response at 20 Percent – 20ms
| Voltage | Before | After | Change | Pass/Fail |
|---|---|---|---|---|
| 12V | 12.107V | 11.886V | 1.83% | Pass |
| 5V | 5.059V | 4.894V | 3.26% | Pass |
| 3.3V | 3.345V | 3.182V | 4.87% | Pass |
| 5VSB | 5.041V | 4.987V | 1.07% | Pass |
Advanced Transient Response at 20 Percent – 1ms
| Voltage | Before | After | Change | Pass/Fail |
|---|---|---|---|---|
| 12V | 12.101V | 11.879V | 1.83% | Pass |
| 5V | 5.058V | 4.879V | 3.54% | Pass |
| 3.3V | 3.343V | 3.167V | 5.26% | Pass |
| 5VSB | 5.041V | 4.996V | 0.89% | Pass |
Advanced Transient Response at 50 Percent – 200ms
| Voltage | Before | After | Change | Pass/Fail |
|---|---|---|---|---|
| 12V | 12.065V | 11.976V | 0.74% | Pass |
| 5V | 5.034V | 4.904V | 2.58% | Pass |
| 3.3V | 3.324V | 3.189V | 4.06% | Pass |
| 5VSB | 5.003V | 4.952V | 1.02% | Pass |
Advanced Transient Response at 50 Percent – 20ms
| Voltage | Before | After | Change | Pass/Fail |
|---|---|---|---|---|
| 12V | 12.060V | 11.932V | 1.06% | Pass |
| 5V | 5.033V | 4.881V | 3.02% | Pass |
| 3.3V | 3.322V | 3.159V | 4.91% | Pass |
| 5VSB | 5.004V | 4.965V | 0.78% | Pass |
Advanced Transient Response at 50 Percent – 1ms
| Voltage | Before | After | Change | Pass/Fail |
|---|---|---|---|---|
| 12V | 12.060V | 11.957V | 0.85% | Pass |
| 5V | 5.033V | 4.881V | 3.02% | Pass |
| 3.3V | 3.322V | 3.169V | 4.61% | Pass |
| 5VSB | 5.004V | 4.955V | 0.98% | Pass |
The transient response at +12V is good for this category's standards. However, deviations on the minor rails are high.
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.
We observe very good results here. All of the slopes rise smoothly, and there are no signs of spikes or voltage overshoots.
Ripple Measurements
Ripple represents the AC fluctuations (periodic) and noise (random) found in the PSU's DC rails. This phenomenon significantly decreases the capacitors' life span because it causes them to run hotter. A 10°C increase can cut into a cap's useful life by 50 percent. 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).
| Test | 12V | 5V | 3.3V | 5VSB | Pass/Fail |
|---|---|---|---|---|---|
| 10% Load | 13.1mV | 7.3mV | 10.4mV | 8.4mV | Pass |
| 20% Load | 22.2mV | 8.0mV | 14.3mV | 10.1mV | Pass |
| 30% Load | 11.7mV | 8.0mV | 12.7mV | 9.7mV | Pass |
| 40% Load | 8.6mV | 7.6mV | 12.6mV | 11.5mV | Pass |
| 50% Load | 8.9mV | 19.9mV | 17.0mV | 12.2mV | Pass |
| 60% Load | 9.5mV | 19.3mV | 19.3mV | 12.7mV | Pass |
| 70% Load | 11.3mV | 13.9mV | 17.9mV | 13.8mV | Pass |
| 80% Load | 12.1mV | 12.3mV | 21.5mV | 16.3mV | Pass |
| 90% Load | 13.3mV | 13.9mV | 22.3mV | 16.9mV | Pass |
| 100% Load | 18.0mV | 16.4mV | 24.9mV | 21.7mV | Pass |
| 110% Load | 21.9mV | 16.0mV | 26.6mV | 22.2mV | Pass |
| Cross-Load 1 | 26.1mV | 14.5mV | 31.6mV | 19.6mV | Pass |
| Cross-Load 2 | 18.2mV | 13.4mV | 17.7mV | 18.6mV | Pass |
Ripple suppression is great on each rail, and without the use of in-cable capacitors.
Ripple At Full Load
Ripple At 110-Percent Load
Ripple At Cross-Load 1
Ripple At Cross-Load 2
EMC Pre-Compliance Testing – Average & Peak EMI Detector Results
Electromagnetic Compatibility (EMC) is the ability of a device to operate properly without disrupting the proper operation of other devices close-by.
Electromagnetic Interference (EMI) represents the electromagnetic energy a device emits. It can cause problems in other close-by devices if it's too high.
We do measure a spike in conducted EMI emissions. However, the test's limits are not breached.
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