FSP Hydro PTM 750W PSU Review

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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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10% Load19.1mV6.0mV6.6mV11.4mVPass
20% Load19.1mV6.3mV6.7mV15.9mVPass
30% Load18.5mV6.2mV6.9mV17.8mVPass
40% Load19.2mV6.5mV7.6mV19.8mVPass
50% Load20.2mV7.6mV7.0mV18.0mVPass
60% Load21.7mV7.6mV7.7mV20.2mVPass
70% Load22.8mV7.6mV7.1mV15.5mVPass
80% Load21.5mV9.4mV10.3mV21.3mVPass
90% Load22.2mV9.8mV10.5mV21.0mVPass
100% Load24.1mV12.6mV10.9mV24.5mVPass
110% Load68.9mV78.3mV78.9mV77.8mVFail
Cross-Load 120.5mV8.7mV8.6mV8.0mVPass
Cross-Load 223.3mV12.0mV10.0mV14.9mVPass

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.

Ripple At Full Load

Ripple At 110-Percent Load

Ripple At Cross-Load 1

Ripple At Cross-Load 2

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Contributing Editor

Aris Mpitziopoulos is a Contributing Editor at Tom's Hardware US, covering PSUs.