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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 a 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% – 20ms
| Voltage | Before | After | Change | Pass/Fail |
| 12V | 12.137V | 11.953V | 1.51% | Pass |
| 5V | 5.040V | 4.949V | 1.81% | Pass |
| 3.3V | 3.327V | 3.182V | 4.36% | Pass |
| 5VSB | 5.075V | 5.029V | 0.90% | Pass |
Advanced Transient Response at 20% – 10ms
| Voltage | Before | After | Change | Pass/Fail |
| 12V | 12.139V | 11.968V | 1.40% | Pass |
| 5V | 5.040V | 4.938V | 2.02% | Pass |
| 3.3V | 3.327V | 3.185V | 4.26% | Pass |
| 5VSB | 5.075V | 5.015V | 1.18% | Pass |
Advanced Transient Response at 20% – 1ms
| Voltage | Before | After | Change | Pass/Fail |
| 12V | 12.140V | 11.957V | 1.51% | Pass |
| 5V | 5.041V | 4.938V | 2.04% | Pass |
| 3.3V | 3.328V | 3.196V | 3.96% | Pass |
| 5VSB | 5.075V | 5.026V | 0.97% | Pass |
Advanced Transient Response at 50% – 20ms
| Voltage | Before | After | Change | Pass/Fail |
| 12V | 12.107V | 11.991V | 0.96% | Pass |
| 5V | 5.027V | 4.933V | 1.86% | Pass |
| 3.3V | 3.316V | 3.165V | 4.54% | Pass |
| 5VSB | 5.034V | 4.989V | 0.89% | Pass |
Advanced Transient Response at 50% – 10ms
| Voltage | Before | After | Change | Pass/Fail |
| 12V | 12.108V | 12.007V | 0.83% | Pass |
| 5V | 5.028V | 4.924V | 2.06% | Pass |
| 3.3V | 3.316V | 3.168V | 4.46% | Pass |
| 5VSB | 5.034V | 4.972V | 1.23% | Pass |
Advanced Transient Response at 50% – 1ms
| Voltage | Before | After | Change | Pass/Fail |
| 12V | 12.109V | 11.999V | 0.90% | Pass |
| 5V | 5.028V | 4.926V | 2.03% | Pass |
| 3.3V | 3.316V | 3.178V | 4.15% | Pass |
| 5VSB | 5.034V | 4.983V | 1.02% | Pass |
This unit's transient response is satisfactory at 12V, quite good at 5V and 5VSB and mediocre at 3.3V. Still, the PSU passes all 3.3V transient tests, but in all cases voltage drops below 3.2V once the transient load is applied.
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.
A small step and a tiny voltage overshoot at 5VSB are present here, but are nothing to worry about.
Power Supply Timing Tests
A power supply generates several signals, which need to be within certain ranges as specified by the ATX spec. If they are not, there can be compatibility issues with other system parts, especially mainboards. Since 2020, a PSU's Power-on time (T1) now has to be lower than 150ms and its PWR_OK delay (T3) has to be within 100 to 150ms to be compatible with the Alternative Sleep Mode.
| T1 (Power-on time) & T3 (PWR_OK delay) | ||
|---|---|---|
| Load | T1 | T3 |
| 20% | 88ms | 134ms |
| 100% | 88ms | 134ms |
The PWR_OK delay is within the 100-150ms region here, so the PSU supports the alternative sleep mode recommended by the ATX spec.
Ripple Measurements
Ripple represents the AC fluctuations (periodic) and noise (random) found in a PSU's DC rails. This phenomenon significantly decreases a capacitors' lifespan because it causes it 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).
| Test | 12V | 5V | 3.3V | 5VSB | Pass/Fail |
| 10% Load | 8.0 mV | 10.3 mV | 11.5 mV | 4.9 mV | Pass |
| 20% Load | 18.2 mV | 10.4 mV | 10.8 mV | 5.5 mV | Pass |
| 30% Load | 10.8 mV | 10.2 mV | 11.2 mV | 6.1 mV | Pass |
| 40% Load | 10.2 mV | 11.3 mV | 11.9 mV | 7.1 mV | Pass |
| 50% Load | 10.4 mV | 12.0 mV | 16.0 mV | 11.3 mV | Pass |
| 60% Load | 10.7 mV | 12.8 mV | 12.5 mV | 8.8 mV | Pass |
| 70% Load | 10.5 mV | 13.5 mV | 12.6 mV | 14.5 mV | Pass |
| 80% Load | 11.0 mV | 13.6 mV | 14.1 mV | 12.5 mV | Pass |
| 90% Load | 11.3 mV | 13.2 mV | 13.8 mV | 11.8 mV | Pass |
| 100% Load | 15.2 mV | 14.7 mV | 15.9 mV | 15.3 mV | Pass |
| 110% Load | 15.5 mV | 17.2 mV | 18.1 mV | 15.3 mV | Pass |
| Crossload 1 | 9.4 mV | 12.1 mV | 12.6 mV | 6.2 mV | Pass |
| Crossload 2 | 8.0 mV | 11.0 mV | 11.3 mV | 5.6 mV | Pass |
| Crossload 3 | 9.0 mV | 10.0 mV | 13.3 mV | 5.4 mV | Pass |
| Crossload 4 | 15.2 mV | 13.8 mV | 14.3 mV | 13.8 mV | Pass |
This PSU might not achieve the outstanding performance of the Corsair RM850x, but still, its ripple suppression is good on all rails.
Ripple At Full Load
Ripple At 110% Load
Ripple At Cross-Load 1
Ripple At Cross-Load 4
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 and/or speakers.
We found a single spur exceeding the limit with an average EMI detector. Everything is fine, though, with a peak detector.
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