Ripple Measurements
To learn how we measure ripple, please click here.
The following table includes the ripple levels we measured on the Capstone-G1200's rails. The 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 | 22.3mV | 7.7mV | 8.8mV | 5.3mV | Pass |
| 20% Load | 26.5mV | 8.3mV | 8.9mV | 5.9mV | Pass |
| 30% Load | 31.0mV | 8.8mV | 10.5mV | 6.3mV | Pass |
| 40% Load | 36.6mV | 9.4mV | 11.2mV | 6.7mV | Pass |
| 50% Load | 42.7mV | 11.2mV | 12.7mV | 7.8mV | Pass |
| 60% Load | 44.9mV | 12.8mV | 13.1mV | 8.1mV | Pass |
| 70% Load | 54.0mV | 15.0mV | 15.2mV | 8.9mV | Pass |
| 80% Load | 62.2mV | 17.4mV | 17.6mV | 9.8mV | Pass |
| 90% Load | 71.2mV | 19.8mV | 18.3mV | 9.7mV | Pass |
| 100% Load | 82.4mV | 21.5mV | 23.6mV | 11.3mV | Pass |
| 110% Load | 92.5mV | 23.2mV | 25.9mV | 12.3mV | Pass |
| Cross-Load 1 | 37.4mV | 20.1mV | 22.2mV | 20.3mV | Pass |
| Cross-Load 2 | 77.5mV | 14.8mV | 15.1mV | 7.3mV | Pass |
Ripple suppression on the +12V rail is flat-out bad. We don't want to see anything above 50mV on this rail, especially in PSUs that cost more than $100. Usually, good PSUs register up to 40mV of ripple at +12V and the extraordinary ones stay below 20mV.
At least ripple suppression on the other rails is good enough. Still, what matters most is the +12V rail's performance, since it's used by most system components nowadays.
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.
