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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 HPT750M'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	19.1mV	6.0mV	6.6mV	11.4mV	Pass
20% Load	19.1mV	6.3mV	6.7mV	15.9mV	Pass
30% Load	18.5mV	6.2mV	6.9mV	17.8mV	Pass
40% Load	19.2mV	6.5mV	7.6mV	19.8mV	Pass
50% Load	20.2mV	7.6mV	7.0mV	18.0mV	Pass
60% Load	21.7mV	7.6mV	7.7mV	20.2mV	Pass
70% Load	22.8mV	7.6mV	7.1mV	15.5mV	Pass
80% Load	21.5mV	9.4mV	10.3mV	21.3mV	Pass
90% Load	22.2mV	9.8mV	10.5mV	21.0mV	Pass
100% Load	24.1mV	12.6mV	10.9mV	24.5mV	Pass
110% Load	68.9mV	78.3mV	78.9mV	77.8mV	Fail
Cross-Load 1	20.5mV	8.7mV	8.6mV	8.0mV	Pass
Cross-Load 2	23.3mV	12.0mV	10.0mV	14.9mV	Pass

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Ripple suppression is great on every rail. It's only during the overload test, when we clearly push the PSU past its limits, that ripple gets out of control (especially on the minor rails). As stated, though, the PSU operates beyond its limits there, and at very high temperatures, so we don't include those results in our final rating.

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.