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be quiet! System Power U9 700W PSU Review


Our cross-load tests are described in detail here.

To generate the following charts, we set our loaders to auto mode through our custom-made software before trying more than 1500 possible load combinations with the +12V, 5V, and 3.3V rails. The load regulation deviations in each of the charts below are calculated by taking the nominal values of the rails (12V, 5V, and 3.3V) as point zero. The ambient temperature is between at 30°C (86°F) to 32°C (89.6°F).

Load Regulation Charts


Efficiency Chart

For the majority of its operation range, the unit delivers within 85-90% efficiency. This is a satisfactory performance, for the standards of the Bronze and ETA-A- efficiency standards.

Ripple Charts

Infrared Images

We apply half-load for 10 minutes with the PSU’s top cover and cooling fan removed before taking photos with our modified FLIR E4 camera that delivers 320×240 IR resolution (76,800 pixels).

The temperatures on the DC-DC converters are high, because we stress those pretty hard with 12 Amperes of load on each of the minor rails. A resistor right behind the NTC thermistor also has high temperature, a clear indication that energy is lost on it.

Speaking of the NTC thermistor, its operating temperature is around 60°C, since it isn’t supported by a bypass relay. This means that in a hot restart and with the bulk cap empty, the inrush current will go through the roof.

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