Ripple Measurements
To learn how we measure ripple, please click here.
The following table includes the ripple levels we measured on the ST1200-PT'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 | 19.9mV | 18.3mV | 36.0mV | 15.0mV | Pass |
| 20% Load | 27.4mV | 20.8mV | 37.3mV | 17.9mV | Pass |
| 30% Load | 30.5mV | 22.9mV | 38.2mV | 20.8mV | Pass |
| 40% Load | 31.1mV | 28.4mV | 44.8mV | 23.4mV | Pass |
| 50% Load | 33.4mV | 30.9mV | 50.6mV | 26.9mV | Fail |
| 60% Load | 34.9mV | 34.8mV | 53.9mV | 29.8mV | Fail |
| 70% Load | 36.3mV | 38.1mV | 61.0mV | 35.6mV | Fail |
| 80% Load | 36.8mV | 41.2mV | 64.7mV | 40.5mV | Fail |
| 90% Load | 38.5mV | 42.7mV | 70.9mV | 41.5mV | Fail |
| 100% Load | 41.8mV | 47.9mV | 76.9mV | 45.8mV | Fail |
| 110% Load | 42.1mV | 48.6mV | 79.5mV | 49.7mV | Fail |
| Cross-Load 1 | 19.1mV | 18.0mV | 32.3mV | 14.2mV | Pass |
| Cross-Load 2 | 44.4mV | 41.8mV | 65.9mV | 42.4mV | Fail |
Ripple suppression on the +12V rail is pretty good, though not top-notch. It's really bad on the minor rails though, especially at 3.3V. The main cause for these poor ripple results is a high ambient temperature. Below 40°C, the PSU's ripple suppression is pretty good on everything except the 3.3V rail. That one needs an ambient close to 30°C to get inside of the 50mV range.
Again, we expect such a high-end PSU to perform well under all temperature conditions. Also, Gigabyte's XP1200M, based on the same platform, demonstrated decent ripple suppression under the same conditions. More than likely, Enhance let something slip by in SilverStone's take on this platform (or we received a lemon, which happens).
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.