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Ripple Measurements
To learn how we measure ripple, please click here.
The following table includes the ripple levels measured from SilverStone's ST75F-PT. According to the ATX specification, the limits are 120mV (+12V) and 50mV (5V, 3.3V and 5VSB).
| Test | 12V | 5V | 3.3V | 5VSB | Pass/Fail |
|---|---|---|---|---|---|
| 10% Load | 8.9mV | 4.8mV | 7.1mV | 4.4mV | Pass |
| 20% Load | 8.9mV | 6.6mV | 6.8mV | 5.6mV | Pass |
| 30% Load | 9.0mV | 8.4mV | 8.9mV | 7.3mV | Pass |
| 40% Load | 10.8mV | 9.7mV | 10.6mV | 8.2mV | Pass |
| 50% Load | 11.3mV | 10.0mV | 11.8mV | 8.3mV | Pass |
| 60% Load | 12.7mV | 10.5mV | 13.0mV | 9.5mV | Pass |
| 70% Load | 13.9mV | 12.8mV | 16.7mV | 10.9mV | Pass |
| 80% Load | 18.8mV | 15.5mV | 29.4mV | 13.6mV | Pass |
| 90% Load | 22.1mV | 18.0mV | 36.0mV | 14.9mV | Pass |
| 100% Load | 25.8mV | 20.8mV | 38.7mV | 16.3mV | Pass |
| 110% Load | 35.3mV | 21.2mV | 41.0mV | 17.2mV | Pass |
| Cross-Load 1 | 10.2mV | 6.9mV | 9.5mV | 4.8mV | Pass |
| Cross-Load 2 | 21.2mV | 21.1mV | 25.0mV | 17.0mV | Pass |
Ripple suppression on the +12V rail is excellent. The same goes for the 5VSB rail. At 5V, ripple is quite low, and only the 3.3V rail holds this PSU back. Good thing it's only used lightly in contemporary systems. Of course, the most important rail is +12V, and that one's ripple-proof.
Ripple Oscilloscope Screenshots
The following oscilloscope screenshots illustrate the AC ripple and noise registered on the main rails (+12V, 5V, 3.3V and 5VSB). The bigger the fluctuations on the screen, the bigger the ripple/noise. We set 0.01V/Div (each vertical division/box equals 0.01V) as the standard for all measurements.
