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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 650 GM’s rails. The limits, according to the ATX specification, are 120mV (+12V) and 50mV (5V, 3.3V, and 5VSB).

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Test	12V	5V	3.3V	5VSB	Pass/Fail
10% Load	12.5mV	8.9mV	9.8mV	4.4mV	Pass
20% Load	13.3mV	9.2mV	10.2mV	4.9mV	Pass
30% Load	15.6mV	10.5mV	11.0mV	6.3mV	Pass
40% Load	19.2mV	12.1mV	11.9mV	7.7mV	Pass
50% Load	22.6mV	14.1mV	13.8mV	9.1mV	Pass
60% Load	26.2mV	16.6mV	15.4mV	10.8mV	Pass
70% Load	30.5mV	18.8mV	17.3mV	12.6mV	Pass
80% Load	34.0mV	21.0mV	19.3mV	14.2mV	Pass
90% Load	37.9mV	23.3mV	21.8mV	15.3mV	Pass
100% Load	41.0mV	25.4mV	23.0mV	17.1mV	Pass
110% Load	45.2mV	27.4mV	24.9mV	18.8mV	Pass
Cross-Load 1	15.6mV	12.0mV	14.9mV	5.4mV	Pass
Cross-Load 2	40.9mV	23.2mV	20.7mV	15.3mV	Pass

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The ripple suppression we observe is not up to today's high-end standards. It's good enough, though, especially when we take into account that this is an SFX-based power supply. Still, it'd be nice to see close to 30mV ripple at +12V and below 20mV on the minor rails under full load.

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.