Articles: Cases/PSU
 

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The +12V rails are wired in a rather odd fashion. According to the industry standard, the 12V2 rail is to feed the CPU only (through a 4-pin ATX12V connector) and the 12V1 feeds all the rest. In the Noisetaker, however, the 12V2 line also powers the mainboard (through the 24-pin connector) whereas the 12V1 is responsible for the rest of the PSU’s peripheral connectors, i.e. the connectors for hard, optical and floppy drives. The main practical consequence of this slightly different wiring may arise if there is an additional and powerful consumer on the 12V2 rail, a graphics card that is permitted to receive up to 75W of power from the PCI Express slot. The latter is located on the mainboard and is powered from the 12V2 rail in this case. As a result, the load on the 12V2 rail may get very close to the limit (18A) if you’ve got a powerful CPU and a PCI Express graphics card in your system, while the 12V1 line will bear but a small load.

The cross-load characteristic of this PSU looks superb. Only the +12V voltage violated the acceptable limits, but it did so at very unlikely load distributions (a very high load on the +5V rail and an almost-zero load on the +12V). In fact, the EG495AX-VE offers as stable voltages as PSUs with independent voltage regulation normally do.

Under full load (485W) the voltage ripple on the +5V, +12V and +3.3V rails was 15, 30 and 20 millivolts, respectively. The pulsation is high-frequency one, with neither a low-frequency constituent (at 100Hz) nor short spikes at the moments the inverter’s transistors are switched over.

The power supply is cooled with two fans: an 80mm one on the rear panel and a 90mm one on the top panel. Both the fans use ball bearings which gives a peculiar tone to the noise the PSU produces. I can’t call this Noisetaker absolutely silent, but it is very quiet indeed and most users are going to be satisfied with its noise characteristics.

A curious feature of this PSU is that the fans keep on working at their min speed after the PC has been shut down until the temperature is below 40°C. It usually takes about 10 minutes for the temperature to reach this mark.

The velocity sensor of the 80mm fan is placed outside and I used it to measure the rotation speed (the sensor gives out precisely two impulses per each rotation of the fan). Unfortunately, I couldn’t measure the speed of the 90mm fan as its velocity sensor is not outside the PSU while the transparent plastic of the blades makes it impossible to use an optical tachometer. Well, these measurements wouldn’t brings too much new info since the speed of the fans is adjusted simultaneously (in Enermax’s earlier power supplies the automatic adjustment only changed the speed of one fan and the other was controlled manually; here, the adjustment systems are joined together and affect both the fans at once). The graph below shows you the dependence of the fan speed on the PSU load for the two extreme positions of the manual control knob.

The objective measurements prove the PSU’s quietness at work, especially when the manual controller is set to the minimum position. Moreover, the speed of the fan doesn’t almost depend on the PSU load at loads below 250-280W.

The efficiency of this PSU is good at 80%. Regrettably, the design of our testbed doesn’t guarantee high efficiency measurement accuracy at high load power which you should be aware of when you compare these numbers to those you get from other sources, especially if those sources don’t employ high-precision measurement techniques, either. These numbers, however, suit fine for comparing this PSU with other PSUs tested on our own testbed, too.

Power factor correction is implemented well in the EG495AX-VE: the power factor is never below 0.9 and is even higher than 0.995 at maximum load (the program we use to process the results rounds the number up to two places behind the dot, so it just gave out the ideal coefficient of “1.00” for the first time in my tests!).

So, the Enermax Noisetaker EG495AX-VE(W) is a very good power supply all around and in its every single feature. It is a high-wattage, quiet and very neatly-made PSU with excellent characteristics. It can easily meet the demands of most PC users.

 
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