The output voltages are very stable except that the +3.3V deflects by 4% from the nominal value under maximum load (the allowable deflection is 5%). The +12V voltage remains very stable at a point slightly higher than the nominal value.
The output voltage ripple is large at max load, but always remains within the acceptable range. The pulsation amplitude is going to decrease at lower loads.
The PSU uses a 135x135x25mm fan from Young Lin Tech Co. (the DFS132512H model). Some say that a larger fan is always a quieter fan. This is not true. The amount of noise depends on the fan speed, on the quality of the bearing, on the design of the PSU, etc. From a PSU developer’s point of view, a large fan may look better since it stretches the entire width of the PSU case and thus cools all of the case volume, leaving no “dead zones”.
The fan speed is kept at about 820rpm up to a load of 600W and then begins to grow up to 1050rpm. As a result, this PSU is very quiet but also rather hot. The difference between the air temperature on its input and output was over 15°C during this test.
The PSU boasts over 85% efficiency through most of the load range, from 150W to the maximum.
Thus, the Cooler Master Real Power Pro RS-850-EMBA leaves a very nice impression. It features a neat assembly, a full set of connectors that is going to be sufficient for any modern system, a very quiet operation, and good electrical parameters. This PSU will be an excellent buy if your PC needs such a high-wattage power source.