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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 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% – 20ms
Voltage | Before | After | Change | Pass/Fail |
---|---|---|---|---|
12V | 12.122V | 11.798V | 2.67% | Pass |
5V | 5.083V | 4.868V | 4.23% | Pass |
3.3V | 3.312V | 2.999V | 9.45% | Fail |
5VSB | 5.076V | 4.957V | 2.34% | Pass |
Advanced Transient Response at 20% – 10ms
Voltage | Before | After | Change | Pass/Fail |
---|---|---|---|---|
12V | 12.124V | 11.657V | 3.85% | Pass |
5V | 5.081V | 4.870V | 4.15% | Pass |
3.3V | 3.311V | 3.006V | 9.21% | Fail |
5VSB | 5.076V | 4.966V | 2.17% | Pass |
Advanced Transient Response at 20% – 1ms
Voltage | Before | After | Change | Pass/Fail |
---|---|---|---|---|
12V | 12.124V | 11.727V | 3.27% | Pass |
5V | 5.080V | 4.888V | 3.78% | Pass |
3.3V | 3.311V | 3.000V | 9.39% | Fail |
5VSB | 5.075V | 4.953V | 2.40% | Pass |
Advanced Transient Response at 50% – 20ms
Voltage | Before | After | Change | Pass/Fail |
---|---|---|---|---|
12V | 12.041V | 11.711V | 2.74% | Pass |
5V | 5.054V | 4.836V | 4.31% | Pass |
3.3V | 3.286V | 2.965V | 9.77% | Fail |
5VSB | 5.029V | 4.906V | 2.45% | Pass |
Advanced Transient Response at 50% – 10ms
Voltage | Before | After | Change | Pass/Fail |
---|---|---|---|---|
12V | 12.043V | 11.652V | 3.25% | Pass |
5V | 5.052V | 4.826V | 4.47% | Pass |
3.3V | 3.285V | 2.971V | 9.56% | Fail |
5VSB | 5.028V | 4.937V | 1.81% | Pass |
Advanced Transient Response at 50% – 1ms
Voltage | Before | After | Change | Pass/Fail |
---|---|---|---|---|
12V | 12.044V | 11.690V | 2.94% | Pass |
5V | 5.049V | 4.847V | 4.00% | Pass |
3.3V | 3.284V | 2.989V | 8.98% | Fail |
5VSB | 5.027V | 4.950V | 1.53% | Pass |
Results 25-29: Transient Response
Transient response is terrible on all rails, especially at 3.3V.
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.
Turn-On Transient Response Scope Shots
There is a small voltage overshoot at 5VSB, which is nothing to worry about. The 12V slopes are good.
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, to be compatible with the Alternative Sleep Mode.
T1 (Power-on time) & T3 (PWR_OK delay) | ||
---|---|---|
Load | T1 | T3 |
20% | 45ms | 289ms |
100% | 78ms | 288ms |
The PWR_OK delay is out of the 100-150ms region, so the PSU does not support the alternative sleep mode, which the ATX spec recommends. We didn't expect this unit to offer ASM support.
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 | 11.8 mV | 10.0 mV | 11.1 mV | 13.1 mV | Pass |
20% Load | 12.8 mV | 10.3 mV | 10.4 mV | 13.0 mV | Pass |
30% Load | 13.3 mV | 8.7 mV | 10.1 mV | 13.3 mV | Pass |
40% Load | 14.0 mV | 7.9 mV | 11.4 mV | 13.6 mV | Pass |
50% Load | 20.4 mV | 9.9 mV | 13.4 mV | 17.7 mV | Pass |
60% Load | 26.7 mV | 12.3 mV | 16.3 mV | 17.4 mV | Pass |
70% Load | 33.3 mV | 14.1 mV | 16.5 mV | 20.3 mV | Pass |
80% Load | 40.0 mV | 15.0 mV | 22.5 mV | 22.1 mV | Pass |
90% Load | 54.2 mV | 17.6 mV | 21.1 mV | 25.0 mV | Pass |
100% Load | 79.2 mV | 24.9 mV | 22.6 mV | 29.5 mV | Pass |
110% Load | 108.5 mV | 33.5 mV | 23.6 mV | 33.3 mV | Pass |
Crossload 1 | 19.2 mV | 17.1 mV | 27.1 mV | 23.3 mV | Pass |
Crossload 2 | 87.2 mV | 22.9 mV | 16.9 mV | 24.6 mV | Pass |
Results 30-33: Ripple Suppression
Ripple suppression is satisfactory on all rails but 12V, where it is much higher than what we would like to see. This platform is close to its limits with 550W output.
Ripple At Full Load
Ripple Full Load Scope Shots
Ripple At 110% Load
Ripple 110% Load Scope Shots
Ripple At Cross-Load 1
Ripple CL1 Load Scope Shots
Ripple At Cross-Load 2
Ripple CL2 Load Scope Shots
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.
The EMI filter does a good job, so conducted EMI emissions stay low.
MORE: Best Power Supplies
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Current page: Transient Response Tests, Timing Tests, Ripple Measurements and EMC Pre-Compliance Testing
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refillable Nice one Aris! I have a request for you. Can you test the Seasonic S12III? It has been circulating around a year now and no one seems to be bothered testing it.Reply -
NightHawkRMX I second this request for the S12iii. Given the popularity of the S12ii (at least back in the day), I am interested to see a review of the successor. I think the fact its RSY made kind of adds to my interest.Reply -
NightHawkRMX Gigabyte GP-P750GM 750 W Review - With an Explosive Attitude | TechPowerUpReply
Well, at least it did not explode.
Gigabyte should just be banned from making PSUs at this point. -
Aris_Mp
Yes this one didn't treat me with fireworks :)NightHawkRMX said:Gigabyte GP-P750GM 750 W Review - With an Explosive Attitude | TechPowerUpWell, at least it did not explode.
Gigabyte should just be banned from making PSUs at this point.