To learn how we measure ripple, please click here.
The following table includes the ripple levels we measured on the 850 BQ's rails. The limits, according to the ATX specification, are 120mV (+12V) and 50mV (5V, 3.3V, and 5VSB).
Ripple suppression at +12V is decent for a value-oriented PSU like this one. However, it could be better on the minor rails. Under full load, the 5V rail is pretty close to its limit. On the other hand, we were pushing the 850 BQ pretty hard in a 45+°C environment.
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 0.01 V/Div (each vertical division/box equals 0.01V) as the standard for all measurements.