Working together with our APC SmartUPS SC 620, this PSU was stable at loads up to 392 watts when powered by the mains and could switch to the UPS’s batteries at loads up to 305 watts.
Cross-Load Voltage Stability
The +12V and +5V voltages are simply immaculate and never deflect from their required levels by more than 2%. There is an anomaly in the zone of low loads, but it's due to a different voltage.
The +3.3V line doesn’t behave well. Its voltage is too high at low loads, exceeding the permissible range even.
This must be a defect of the particular sample of the PSU. It’s hard to believe that one voltage can be that worse than the others in a PSU with dedicated voltage regulation.
Output Voltage Ripple
The output voltage ripple is rather strong, but meets the industry requirements.
The same goes for the voltage ripple at the double frequency of the mains.
Efficiency and Power Factor
At the reference loads of 20%, 50% and 100%, the Enhance ATX-0340N was 85.7%, 89.6% and 90.5% efficient. It is an 80 PLUS Silver unit indeed. It doesn’t meet the Gold requirements at low and medium loads but its efficiency is actually as high as Platinum at the maximum load.
The peak efficiency of 91.4% was achieved at a load of 268 watts.
The power factor is about 97%, which is somewhat lower than the most efficient implementations of active power factor correction.
The standby source copes with its job, always staying within 0.1 volts of the required level.
The Enhance ATX-0340N is an interesting option for compact system cases but our impression was somewhat spoiled by its +3.3V voltage which is too far off the required level in the typical load range.