Connected to APC SmartUPS SC 620, this PSU was stable at loads up to 392 watts when powered by the mains but could only switch to the UPS’s batteries at a load of 280 watts.
Output Voltage Stability
The +12V and +3.3V voltages do not deflect by more than 3% from their ideal levels except that the +3.3V voltage gets more unstable when there is unrealistically high load on the +3.3V rail and a high load on the +12V rail.
The +12V rail behaves differently than in most other high-wattage PSUs where this voltage deflects more at low loads and less at high loads. Here, the +12V voltage keeps within 1% from its default level at loads up to 500 watts but fluctuates more at higher loads.
The +5V voltage is the least stable of all, deflecting by 4-5% from 5 volts when there’s a high load on the +12V rail.
Output Voltage Ripple
The high-frequency voltage ripple is close to the permissible limits on each power rail, occasional spikes even shooting above those limits on the +5V rail.
The same goes for the low-frequency ripple.
Enhance should do something about this parameter as the EPS-1812GA4 barely meets the industry standard.
Temperature and Noise
The PSU is cooled by a DFB132512H fan from Young Lin Tech. It’s an 11-blade 135mm model with a rated speed up to 1700 RPM.
The fan starts out at 720 RPM and doesn’t change this speed until a load of 450 watts. Then it accelerates in a linear manner up to 1400 RPM at 950 watts and maintains this speed until full load. Thus, the fan doesn’t even reach its maximum rated speed. As a result, the EPS-1812GA4 turns out to be the quietest of the four PSUs. It is virtually silent at loads up to 700 watts and does not get uncomfortable even at full load.
Efficiency and Power Factor
The power factor is just what you can expect from a modern PSU with active power factor correction.
As for the efficiency, my tests suggest that this model can meet the 80+Gold requirements even though it lacks official certification.
It is 3.2% and 0.8% more efficient than required at loads of 20% and 50%. At full load it is 0.1% less efficient than necessary, but this may be due to measurement inaccuracies, especially as it is 87.3% efficient only 26 watts short of full load.
+5V Standby Source
The standby source is blameless.
The Enhance EPS-1812GA4 can boast good electrical and acoustic properties, but has short fixed cables and a rather high level of output voltage ripple.
If Enhance can get rid of the mentioned downsides without compromising the model’s quietness, it would be a very good buy.