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Transient Response Tests, Timing Tests and Ripple Measurements
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
| Voltage | Before | After | Change | Pass/Fail |
|---|---|---|---|---|
| 12V | 12.029V | 11.913V | 0.96% | Pass |
| 5V | 5.056V | 4.942V | 2.25% | Pass |
| 3.3V | 3.347V | 3.183V | 4.90% | Pass |
| 5VSB | 5.027V | 4.976V | 1.01% | Pass |
Advanced Transient Response at 20% – 20ms
| Voltage | Before | After | Change | Pass/Fail |
|---|---|---|---|---|
| 12V | 12.030V | 11.856V | 1.45% | Pass |
| 5V | 5.054V | 4.921V | 2.63% | Pass |
| 3.3V | 3.346V | 3.147V | 5.95% | Pass |
| 5VSB | 5.025V | 4.955V | 1.39% | Pass |
Advanced Transient Response at 20% – 1ms
| Voltage | Before | After | Change | Pass/Fail |
|---|---|---|---|---|
| 12V | 12.030V | 11.929V | 0.84% | Pass |
| 5V | 5.052V | 4.920V | 2.61% | Pass |
| 3.3V | 3.346V | 3.145V | 6.01% | Pass |
| 5VSB | 5.024V | 4.951V | 1.45% | Pass |
Advanced Transient Response at 50% – 200ms
| Voltage | Before | After | Change | Pass/Fail |
|---|---|---|---|---|
| 12V | 12.015V | 11.902V | 0.94% | Pass |
| 5V | 5.046V | 4.934V | 2.22% | Pass |
| 3.3V | 3.341V | 3.177V | 4.91% | Pass |
| 5VSB | 5.005V | 4.941V | 1.28% | Pass |
Advanced Transient Response at 50% – 20ms
| Voltage | Before | After | Change | Pass/Fail |
|---|---|---|---|---|
| 12V | 12.015V | 11.881V | 1.12% | Pass |
| 5V | 5.043V | 4.902V | 2.80% | Pass |
| 3.3V | 3.340V | 3.143V | 5.90% | Pass |
| 5VSB | 5.002V | 4.923V | 1.58% | Pass |
Advanced Transient Response at 50% – 1ms
| Voltage | Before | After | Change | Pass/Fail |
|---|---|---|---|---|
| 12V | 12.015V | 11.897V | 0.98% | Pass |
| 5V | 5.042V | 4.916V | 2.50% | Pass |
| 3.3V | 3.339V | 3.136V | 6.08% | Fail |
| 5VSB | 5.001V | 4.915V | 1.72% | Pass |
The transient response is not good enough for the standards of this category. The 1000 G3 easily takes the lead here. Finally, the 3.3V rail's performance is disappointing since its voltage drops too low 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.
There is a small voltage overshoot at 5VSB, while the other two waveforms are smooth enough.
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.
| T1 (Power-on time) & T3 (PWR_OK delay) | ||
|---|---|---|
| Load | T1 | T3 |
| 20% | 64ms | 296ms |
| 50% | 50ms | 296ms |
The Power-on time is low, but the PWR_OK delay is higher than 150ms, so the PSU is not compatible with the alternative sleep mode.
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).
| Test | 12V | 5V | 3.3V | 5VSB | Pass/Fail |
|---|---|---|---|---|---|
| 10% Load | 10.1 mV | 5.3 mV | 14.8 mV | 10.0 mV | Pass |
| 20% Load | 8.9 mV | 5.4 mV | 14.0 mV | 9.9 mV | Pass |
| 30% Load | 10.3 mV | 5.7 mV | 15.9 mV | 10.8 mV | Pass |
| 40% Load | 10.6 mV | 5.9 mV | 16.9 mV | 11.0 mV | Pass |
| 50% Load | 12.4 mV | 6.3 mV | 18.5 mV | 11.3 mV | Pass |
| 60% Load | 13.0 mV | 7.0 mV | 19.1 mV | 11.9 mV | Pass |
| 70% Load | 14.1 mV | 7.7 mV | 21.2 mV | 12.7 mV | Pass |
| 80% Load | 14.7 mV | 7.9 mV | 22.1 mV | 12.6 mV | Pass |
| 90% Load | 15.3 mV | 8.6 mV | 23.1 mV | 13.5 mV | Pass |
| 100% Load | 22.6 mV | 10.7 mV | 30.0 mV | 18.8 mV | Pass |
| 110% Load | 72.7 mV | 43.7 mV | 159.3 mV | 92.0 mV | Fail |
| Crossload 1 | 10.0 mV | 7.3 mV | 18.2 mV | 11.6 mV | Pass |
| Crossload 2 | 18.1 mV | 10.1 mV | 29.9 mV | 18.1 mV | Pass |
The ripple suppression is good with up to 100% load. Nonetheless, clearly the platform cannot handle our 110% load scenario at high operating temperatures, since the ripple at 3.3V and 5VSB exceeds the limits.
Ripple At Full Load
Ripple At 110% Load
Ripple At Cross-Load 1
Ripple At Cross-Load 2
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