be quiet! SFX Power 2 300W Power Supply Review

by - 6 years ago

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Ripple


Noise and Ripple can easily be measured by an oscilloscope. These show how much voltage fluctuation there is on a particular rail. We tested the rail stability of the 3.3 volt, 5 volt and 12 volt rails using an identical time and millivolt scale for all graphs. millivolt ripple is measured by the peak to peak size of the voltage curve.

sample_scalev2

Sample Ripple Graph

The latest ATX 12 volt version 2.3 specifications state that ripple from peak to peak must be no higher than 50 millivolts for the 3.3 volt and 5 volt rails, while the 12 volt rail is allowed up to 120 millivolts peak to peak to stay within specifications. Millivolt figures are stated to the closest increment of 5 given their variability.

Load (%) 3.3V Ripple 5V Ripple 12V Ripple
20  7mV  5.2mV  14.6mV
40  8.6mV  6.6mV  18.4mV
60  11mV  8.8mV  23.2mV
80  13.8mV  12.2mV  31.2mV
100  16.6mV  12.8mV  35.8mV

Ripple suppression was excellent for such a compact unit; less than 40 mV on the 12 volt and around 15mV on the other main rails is an excellent result. We see results similar to this on higher end ATX units.

3.3 volt @ 100%
bequiet_sfxpower2_100_3v

5 volt @ 100%

bequiet_sfxpower2_100_5v

12 volt @ 100%

bequiet_sfxpower2_100_12v

Article Index

  1. Introduction and Packaging
  2. A Closer Look - Exterior
  3. A Closer Look - Interior
  4. Test Procedure
  5. Efficiency, PFC and Voltage Regulation
  6. Ripple Testing
  7. OPP and Max Wattage
  8. Fan Speed
  9. Final Thoughts
  10. View All

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