Articles: Cases/PSU

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Besides the cables, the PSU comes with two “Enermax” stickers (black and white) and a strap for wearing something on the neck. The latter can be used for your mobile phone or mp3 player but there’s nothing inside the PSU box that could be worn that way. This is the first time I see accessories supplied with a PSU that do not have any relation whatsoever to powering something.

Despite the considerable increase of the overall wattage of the unit over the EG495XA-VE (by nearly 30%), the allowable total load on the +12V rails has only increased from 32A to 36A. What’s strange, the declared max load on the 12V1 and 12V2 lines is 22A, although this violates the requirements of the EN-60950 standard the very division into 12V1 and 12V2 rails was implemented for. The allowable load on the low-voltage rails has even decreased, from 32A to 28A for the +3.3V. It doesn’t matter much for today’s computer systems, though.

The cross-load diagram for this power supply is nearly an accurate rectangle. There is no beveled corner in the right part of the diagram where the tested PSU usually reaches its maximum output power because with the Liberty ELT620AWT the sum of the maximum loads on each rail is a little bigger than the maximum PSU load overall. The voltages are so stable that they only go out of the required limits in the left part of the graph when there is a great load misbalance towards the +5V rail. Like the Noisetaker, this PSU ensures an excellent stability of the output voltages as you might have expected considering the similarity of their internal design.

I also checked the Liberty out for its compatibility with uninterruptible power supplies. Many users have reported that some PC power supplies with the full range of input voltages supported (i.e. the entire range from 90 to 265V without your having to manually switch between 115 and 230V) cannot normally work with UPSes. The moment the PC switches over to the UPS batteries, the overload protection in the power supply shuts the whole system down.

So, I checked the Liberty ELT620AWT with two UPSes: APC BackUPS CS350 and APC SmartUPS SC620. The maximum load power of the PSU was 200W and 175W as it worked from the electric mains and from the batteries, respectively, when the former UPS indicated overload. With the latter UPS, the numbers were 360W and 330W, respectively. No problems were observed at the moments the system switched over from the electric mains to the UPS batteries.

One 120mm ball-bearings fan is employed to cool this power supply. Unlike with the Noisetaker, there’s no manual speed controller in the Liberty and the speed is growing up linearly starting from a 150W load (the Noisetaker’s fan speed was constant until near 300W). I wouldn’t say the Liberty is louder than the Noisetaker, though. On one hand, the hiss of the air the fan is pumping through becomes perceptible at high loads, but on the other hand, the bearing of one 120mm fan produces much less noise than the bearings of two fans in the Noisetaker. Keep it in mind too that the load of 620W is excessive for a majority of today’s PC systems. The maximum power consumption of an average gaming computer varies within 200-250W and even SLI configurations feel well with a 400W PSU. In other words, there’s a rather small chance of the Liberty’s fan to speed up to its maximum in your particular computer.

Enermax declares for its Liberty series PSUs an efficiency of 80% in a load range of 30-100% of the maximum, i.e. from about 200W and higher in this case, and this is really so. The efficiency is 80% at loads of 150-160W and never goes below this level even though it diminishes somewhat at loads of 450W and higher.

So, the Enermax Liberty, like the above-described Noisetaker, leaves a very positive impression both subjectively and objectively, i.e. with its performance in tests. This is a top-quality, high-wattage and quiet power supply that can easily power up almost any PC configuration imaginable.

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