Ripple Measurements
To learn how we measure ripple, please click here.
The following table includes the ripple levels we measured on the rails of the 550 GS unit. The limits, according to the ATX specification, are 120mV (+12V) and 50mV (5V, 3.3V and 5VSB).
| Test | 12V (mV) | 5V (mV) | 3.3V (mV) | 5VSB (mV) | Pass/Fail |
|---|---|---|---|---|---|
| 10% Load | 10.9 | 5.1 | 8.2 | 4.9 | Pass |
| 20% Load | 23.7 | 5.5 | 8.4 | 5.6 | Pass |
| 30% Load | 21.1 | 6.3 | 9 | 5.9 | Pass |
| 40% Load | 30.6 | 7 | 10.6 | 7.1 | Pass |
| 50% Load | 33.1 | 7.6 | 10 | 10.5 | Pass |
| 60% Load | 41.1 | 8.9 | 10.8 | 10.6 | Pass |
| 70% Load | 43.1 | 9.6 | 11.9 | 10.8 | Pass |
| 80% Load | 48.6 | 10.1 | 12.1 | 10.2 | Pass |
| 90% Load | 68.8 | 11.5 | 12.4 | 10.3 | Pass |
| 100% Load | 69.6 | 14.3 | 15.5 | 11.9 | Pass |
| 110% Load | 72.7 | 16.5 | 16.5 | 12.9 | Pass |
| Cross-Load 1 | 15.5 | 5.5 | 6.6 | 12 | Pass |
| Cross-Load 2 | 69.6 | 14.1 | 14.4 | 11.3 | Pass |
Ripple suppression on the minor rails was fantastic. But on the +12V rail, which is the most important one, EVGA's 550 GS didn’t look like a Seasonic implementation. This is the first time we have seen a Seasonic unit reach 70mV ripple at +12V. Although that's still far below the ATX limit, we don’t like to see measurements above 50mV from modern platforms like this one. We can think of two reasons for the increased ripple level at +12V, taking into account that Seasonic knows how to restrict it. The company was either after higher efficiency levels and didn’t use enough filtering capacitors, or just wanted to reduce production costs (Japanese caps are expensive). Whatever the reason, we believe that in the next revision of this platform, Seasonic should rectify the situation, as ripple suppression is among the most important performance factors.
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.
