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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 SX700-LPT's rails. The limits, according to the ATX specification, are 120mV (+12V) and 50mV (5V, 3.3V and 5VSB).
| Test | 12V | 5V | 3.3V | 5VSB | Pass/Fail |
|---|---|---|---|---|---|
| 10% Load | 9.5mV | 7.4mV | 10.8mV | 4.6mV | Pass |
| 20% Load | 14.6mV | 10.4mV | 14.1mV | 5.8mV | Pass |
| 30% Load | 15.0mV | 10.9mV | 16.5mV | 6.7mV | Pass |
| 40% Load | 16.4mV | 11.1mV | 17.1mV | 7.7mV | Pass |
| 50% Load | 21.3mV | 13.9mV | 21.0mV | 7.9mV | Pass |
| 60% Load | 24.7mV | 15.7mV | 23.1mV | 9.2mV | Pass |
| 70% Load | 29.9mV | 15.9mV | 26.8mV | 9.3mV | Pass |
| 80% Load | 35.7mV | 19.6mV | 28.7mV | 12.7mV | Pass |
| 90% Load | 42.8mV | 20.0mV | 28.8mV | 13.6mV | Pass |
| 100% Load | 52.8mV | 23.5mV | 36.2mV | 15.9mV | Pass |
| 110% Load | 479.3mV | 46.3mV | 46.4mV | 43.4mV | Fail |
| Cross-Load 1 | 18.2mV | 16.5mV | 29.1mV | 5.9mV | Pass |
| Cross-Load 2 | 55.6mV | 21.8mV | 28.6mV | 17.5mV | Pass |
Ripple suppression at +12V is decent up to the full load test, but during our overload test (110% load) ripple goes out of control with almost 0.5V deviations! Such high ripple can easily damage other components inside of your PC. Despite the out-of-control +12V rail, the minor rails keep ripple in-spec during the overload test.
We should stress that SilverStone clearly states this unit's peak load is 750W and not the 770W we applied (following methodology that we use in every PSU review). In order to be fair, we also conducted an overload test with 750W load and didn't notice any ripple suppression problems at +12V. Apparently, 20W of additional load are enough to cause chaos.
Thanks to the higher efficiency and decreased thermal load of 230V input, ripple suppression with 110% load is normal.
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 0.01 V) as the standard for all measurements.
