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Ripple Measurements
To learn how we measure ripple, please click here.
The following table includes the ripple levels we measured on the ST75F-GS V2's rails. The limits, according to the ATX specification, are 120mV (+12V) and 50mV (5V, 3.3V and 5VSB).
| Test | 12 V | 5 V | 3.3 V | 5VSB | Pass/Fail |
|---|---|---|---|---|---|
| 10% Load | 10.4mV | 5.4mV | 8.1mV | 7.1mV | Pass |
| 20% Load | 11.8mV | 6.5mV | 11.2mV | 7.7mV | Pass |
| 30% Load | 11.6mV | 8.3mV | 15.5mV | 8.8mV | Pass |
| 40% Load | 11.3mV | 8.3mV | 11.5mV | 9.4mV | Pass |
| 50% Load | 13.2mV | 9.5mV | 11.8mV | 11.0mV | Pass |
| 60% Load | 15.0mV | 11.3mV | 11.5mV | 12.2mV | Pass |
| 70% Load | 16.8mV | 11.4mV | 11.9mV | 14.0mV | Pass |
| 80% Load | 19.2mV | 12.1mV | 13.8mV | 15.9mV | Pass |
| 90% Load | 23.7mV | 13.1mV | 14.1mV | 16.9mV | Pass |
| 100% Load | 32.8mV | 40.5mV | 49.9mV | 29.3mV | Pass |
| 110% Load | 39.3mV | 42.9mV | 53.5mV | 30.6mV | Fail |
| Cross-Load 1 | 12.0mV | 8.0mV | 15.1mV | 29.6mV | Pass |
| Cross-Load 2 | 33.0mV | 42.4mV | 51.2mV | 24.2mV | Fail |
Operating temperature greatly affects ripple suppression under high loads. Up to the 90% load test, the PSU registered low ripple on all of its rails. But during the full load and overload tests, we noticed spikes that hugely affected ripple suppression, especially on the minor rails. After enough test sessions, we found out that if you keep the max operating temperature close to 40 °C (SilverStone's specified ceiling), then ripple suppression is great on all rails. If you push beyond 42 to 43 °C, though, random spikes start showing up.
Since we also tested the unit with 230V, at that input voltage, even at 45 °C and after a prolonged period full-load testing, the ripple on all rails was low. There was no sign of spikes. Apparently, the higher efficiency levels with 230V aren't as stressful, despite the tough conditions.
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.
