Working together with our APC SmartUPS SC 620, this PSU was stable at loads up to 388 watts when powered by the mains. They could switch to the UPS’s batteries at loads up to 330 watts.
Cross-Load Voltage Stability
The +12V rail is rock-solid, its voltage never being more than 1% off the required level!
The +5V voltage is just as stable. It is not going to be more than 2% off in the typical load range.
The +3.3V voltage can only get 3% off the required level when the load on the +12V rail is close to the maximum. Overall, the Chieftec SPS-650C must be praised for delivering extremely stable voltages.
Output Voltage Ripple
The high-voltage ripple is noticeable on each rail but is always within the permissible range.
It’s even better at the double frequency of the mains: the ripple is weaker on the +12V rail and much weaker on the +3.3V and +5V rails.
Temperature and Noise
The Chieftec SPS-650C is cooled by a 7-blade Yate Loon fan (D14SM-12, 140 mm, 1400 RPM). Like the fan of the Chieftec CTG-600-80P, it runs on a sleeve bearing but can’t match the latter’s noiselessness. Well, this fan is quiet, too. You can hear some unwanted sounds only if you put your ear right next to the PSU case.
The fan regulation algorithm is just perfect. The fan works at a noiseless 800 RPM until a load of 550 watts. Then it accelerates suddenly, yet only to 1200 RPM.
Take note that the difference in temperature between the incoming and outgoing air remains the same after the fan starts to accelerate. This seems to be perfect regulation: the fan is comfortable at most loads yet protects the PSU from overheat.
So, the Chieftec SPS-650C is one of the quietest in its class. It is virtually silent at most loads and is quieter than most of its competitors at full load.
Efficiency and Power Factor
The PSU was 88.6%, 89.9% and 88% efficient at the reference loads of 20%, 50% and 100%, respectively. Its peak efficiency of 90.3% was observed at loads of 378 to 402 watts.
These results almost match the 80 PLUS Gold requirements and meet the Silver certification by a large margin.
The power factor is about 99%, which is a good result, too.
The standby source copes well, but its voltage is 4% off the required level at full load.
The Chieftec SPS-650C is very quiet at any load and boasts exemplary stability of voltages, high efficiency and reasonable pricing. Our minor complaints about secondary electrical parameters (which all meet the requirements of the industry standard, though) and cables have no chance to blemish the numerous advantages this model has to offer.