The +12V voltage sags when the other rails are under load, but is stable enough in the typical load range.
The +5V voltage is even more stable. It only goes far from the required level when the load is very high or very low.
The +3.3V voltage is the most stable of all.
It must be noted that this PSU can only power up the weakest of our reference PC configurations but the voltages would all be very stable (within 1% of the required levels) with that configuration at full load.
Output Voltage Ripple
The Elite Power RS-400-PSAP-J3 meets the requirements in terms of output voltage ripple. The high-frequency ripple is conspicuous on the +12V rail, less conspicuous on the +3.3V rail and almost invisible on the +5V rail.
The +12V rail is also the noisiest at the double frequency of the power mains. The +3.3V rail is the most stable here. The output voltage ripple is within the norm on each rail, though.
Temperature and Noise
The PSU is cooled by a 7-blade 120mm Yate Loon fan (D12SM-12) that has a rated speed of 1650 RPM.
The fan starts out at about 1300 RPM, which is not quiet. On the other hand, it doesn’t accelerate much at higher loads, never reaching even 1400 RPM.
Efficiency and Power Factor
Cooler Master’s PSU is somewhat more efficient than FSP’s 60PN(PF) and 60THN-P series products and is comparable to FSP’s later Optima series which is based on the same platform. It is 80% efficient at the maximum, which isn’t high by today’s standards. Its power factor is typical of passive PFC: about 80% at low loads and somewhat lower at high loads.
The standby voltage is very stable, fluctuating by no more than 1%.
If you need to power an entry-level PC and do not care about noise, Cooler Master’s Elite Power RS-400-PSAP-J3 is going to be a good choice. On the other hand, if you don’t mind using power adapters, you can prefer the original FSP ATX-350N and have the same specs (except for fewer connectors) for less money. Even the higher-wattage FSP ATX-450N costs less than this Cooler Master (yet the latter has more connectors anyway).