Enermax Liberty 620w Modular ATX PSU

Load Testing

In order for the results from all current and future PSU reviews to remain fair and comparable, Overclock3D uses a custom built Power Supply load stress tester.

The tester will be placing the following loads on each of the Liberty 620w rails:

+3.3v – 20a Load
+5.0v – 20a Load
+12v1 – 20a Load
+12v2 – 10a Load

The results are collected from a Mastech MAS-345 Multimeter which logs its readings via RS232 to a PC.

As we can see from above, all rails were fairly stable, with the most noticeable fluctuation occurring on the +5v rail. Despite this, the rail remained well within ATX specifications.

Both of the +12v rails dipped by around 0.20v taking them down to around 11.9v. While this wouldn’t cause any problems what so ever, this is the kind of situation where adjustable potentiometers could have come in handy to increase the rails back up within the 12.0v mark.

Efficiency Testing

Efficiency tests are performed by measuring the wattage consumed by the power supply at the mains against the power (in watts) consumed by the OC3D power supply stress tester.

The results may not be as accurate as those produced by professional testing equipment, but will certainly come in handy when comparing several power supplies against each other.

The Liberty 620w was placed under a load of 526 watts. This counts for a total of 85% of the power supplies rated output. At this load, the power supply required 638 watts from the mains to produce the 526 watts required by our custom made power supply tester.

Therefore the efficiency of this power supply can be found by a simple equation: (526 / 638) * 100 that works out to be an efficiency rating of 82.4%, which is very close to the 80% efficiency rating given by Enermax.

Noise Testing

Cooling the Liberty 620w is a 120mm fan manufactured by Globefan. This fan is rated at 39dBA when running at full speed which may give the impression that this unit is going to be quite noisy.

However, under idle conditions the fan is whisper quiet, and only audible if you have the unit close to your ear. With the unit installed inside a standard pc case, I was unable to hear the unit at all.

Under heavy load conditions the Liberty steps up the fan speed significantly. This does cause an increase in noise, but not to the point where it becomes an irritation. I’d estimate the noise output under load to be around 25dBA.