Fan Speed Management
The described PSUs come with dual fans as is indicated by the DF suffix in the model names.
The main fan is a Globe Fan with a form-factor of 135x135x25 millimeters.
The auxiliary fan is a Globe Fan with a form-factor of 80x80x15 millimeters.
The junior model has very good noise characteristics: both fans are rotating at very modest speeds until a load of 600 watts. This PSU can be considered as truly quiet.
The 1000W model behaves in the same manner. It is very quiet at loads below 550W. Then its fans accelerate quickly, resulting in an appropriate, but quite acceptable, increase in noise.
The 1200W model differs from the others. It has higher initial speeds of the fans. And while the previous two models get just a little bit noisier at loads higher than 600W, this one begins to produce a distinct hissing of the air then. There are no other sounds, however, so this noise is quite comfortable overall.
Thus, the Chieftec Super Series PSUs are very quiet, especially for their impressive wattage. And they also show that there is no point in choosing a higher-wattage PSU than you actually need in order to have less noise. This erroneous opinion is widespread among customers, but you can see that replacing the 850W model with the 1000W one won’t change anything in terms of noisiness. And the 1200W model will produce even more noise.
Efficiency and Power Factor
The three models all have similar results in this test, so I will again limit myself to one diagram only.
The PSUs are very efficient, reaching an efficiency of 87% at loads of a few hundred watts. The graph declines towards the right part of the diagram, but does not cross the 80% line.
The only drawback of these three PSUs is that they cannot work normally with UPSes. Otherwise, Chieftec’s Super Series products are top class. They boast high quality of manufacture, excellent electrical parameters, a sufficient selection of cables, and quiet operation even at high loads.