As we’ve mentioned above, the PSU is identical to the original CWT model in its specifications. And we can’t find any problem about them. The PSU can yield almost all of its output power via the most important +12V rail (it is not split into multiple virtual lines, which is good, too). The load capacity of the other rails will easily meet the requirements of any possible PC configuration.
Like its Channel Well progenitor, the Chieftec BPS-850C2 complies with the 80 PLUS Bronze standard.
Working with our APC SmartUPS SC 620, the Chieftec BPS-850C2 was stable at loads up to 385 watts when powered by the mains but could only switch to the UPS’s batteries at 285 watts.
Cross-Load Voltage Stability
The most important +12V voltage remains within 2% of the required level at most loads. There is but a tiny fragment of the diagram where it is 3% off at low loads.
The +5 voltage is just as good. Its 3% area is larger than with the +12V voltage, but lies in the zone of very high loads on the +3.3V and +5V rails which are unlikely to occur in a real-life computer.
The +3.3V voltage is the least stable of all. It can be 3% off the required level in the typical load range and up to 4% off at other loads.
Output Voltage Ripple
The high-frequency ripple is rather strong, barely meeting the industry requirements on the +3.3V and +12V rails. The rather frequent voltage spikes on the +5V rail are obviously beyond the permissible range.
The low-frequency ripple is somewhat weaker, but the overall picture is the same.
Temperature and Noise
The Chieftec BPS-850C2 is cooled by a 7-blade 140mm fan from Young Lin Tech (it is the D14BH-12 model with a rated speed of 2800 RPM). Its impeller is partially covered with a piece of plastic to optimize air flows inside the PSU case.
The fan starts out at a low speed of 800 RPM. It maintains the same speed until a load of 350 watts and then accelerates linearly, reaching 1900 RPM at 850 watts. The PSU’s noise becomes uncomfortable at 1000 RPM and 450 watts.
Overall, the BPS-850C2 is rather quiet at medium loads, but most of its opponents are going to be quieter at high loads.
Efficiency and Power Factor
The BPS-850C2 was 20%, 50% and 100% efficient at the reference loads of 87.4%, 90.4% and 85.9% and thus meets not only 80 PLUS Bronze but even the 80 PLUS Silver requirements. Its peak efficiency of 91% could be observed at a load of 250 watts.
The power factor is over 99% at high loads, which is a perfect performance for a PSU with active power factor correction.
We can see no problem about the standby source.
The Chieftec BPS-850C2 is a high-efficiency PSU with modular design, stable voltages and reasonable pricing. However, it is noisy at high loads and its output voltage ripple is rather too strong.