Working with our APC SmartUPS SC 620, this PSU was stable at loads up to 415 watts when powered by the mains but could only switch to the UPS's batteries at loads up to 292 watts.
Cross-Load Voltage Stability
The +12V voltage is never more than 3% off the required level. This 3% deflection only occurs when the computer is idle.
The +5V voltage is even better, never deflecting by more than 2%.
The +3.3V voltage is the least stable of all. Fortunately, it doesn’t go out of the permissible range, as that of the the above-discussed Enhance, but can be 4% off at low loads.
Output Voltage Ripple
Seasonic’s PSUs have always been good in this test, and this model is no exception.
The high-frequency voltage ripple is very weak, especially on the +12V rail.
The voltage ripple at the frequency of 2 milliseconds is weak as well.
Efficiency and Power Factor
At the reference loads of 20%, 50% and 100%, the Seasonic SS-460FL is 88.1%, 91.8% and 92.1% efficient. This complies with the 80 PLUS Gold requirements the PSU is certified for.
The peak efficiency of 93.4% was achieved at a load of 270 watts.
The power factor is about 97% at high loads, which is somewhat lower than the best implementations of active power factor correction.
The standby source is okay, its voltage never being more than 2% off the required level.
The Seasonic SS-460FL is in fact blameless, save for its indecent price. Its +3.3V voltage might be more stable, yet it's always within the required range anyway.