A 12cm Protechnic Electric MGA12012HS-025 fan is installed in this PSU. The max rotational speed of this fan is 2500rpm at 38.3dB noise. My measurements proved that the fan reaches its max speed (and noise) when there is the highest load on the power supply:

On one hand, the fan speed is adjusted very effectively. It is steadily increased depending on the load (you may remember that some older models from FSP used to change the speed of their fan in a sudden jump from min to max at a load of about 150-250 watts). On the other hand, this power supply is not quiet. The fan is rather fast, and its air stream is audible even at 1500rpm.

The PSU’s efficiency is good, although not the best possible (about 75-80%). The power factor is quite typical for a product with passive PFC, reaching 0.83 at the maximum. To tell you the truth, it doesn’t differ much from the power factor of PSUs without any kind of correction.

As I wrote above, the AX500-A is a 460W unit, despite the number in its name. The allowable load power on the +5V and +3.3V rails is up to 150W (well, my measurements above have already shown that modern computers would be satisfied even with half of that power); the maximum allowable currents on +5V, +3.3V and +12V rails are 28, 30 and 15+16 amperes, respectively (like in other ATX12V 2.0 units, the +12V rail is split in two outputs here).

The cross-load characteristics of the PSU are good, but like other units without dedicated voltage regulation it cannot boast an ideal stability of the output voltages. The +12V voltage fluctuates the most, from 11.4 to 12.6V.

On the other hand, if we take a look at the four dots on the diagram that correspond to the min and max consumption of the above-described Athlon 64 and Pentium 4 systems (the measurements I performed at the beginning of the article were done for these four dots), you can see that the output voltages of the PSU are the same for each dot – even the relatively unstable +12V voltage changes by only about 1% from one dot to another.