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).
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.