The specs are identical to those of the 1000W model except for the load capacity of the +12V rail. We can note that the Silent Pro M2 850W has a redundant load capacity of the +5V and +3.3V rails combined: a modern computer can hardly need even one third of the permissible maximum of 180 watts. However, considering that the +12V rail can yield almost all of the PSU’s total output power, leaving a mere 34 watts to the other rails, this is not a downside but just a not very required feature.
The Silent Pro M2 850W complies with the 80 PLUS Silver standard.
Working together with our APC SmartUPS SC 620, the PSU was stable at loads up to 402 watts when powered by the mains but could only switch to the UPS’s batteries at 290 watts. This is a little better than the performance of the 1000W model from the same series in this test.
Cross-Load Voltage Stability
The most important +12V rail sports immaculate stability. It remains within 1% of the required level at most loads and is never even 2% off.
The +5V voltage remains within 3% of the required level in the typical load range. Except for high loads on the +12V rail, the +5V voltage is no more than 2% off.
Although the +3.3V voltage may deflect by up to 5%, which is the permissible maximum, it remains within 3% in the typical load range.
Overall, the Silent Pro M2 850W performs like its 1000W cousin except that its +12V voltage is somewhat more stable.
Output Voltage Ripple
The high-frequency voltage ripple is within the norm on each power rail. It is very weak on the +5V and +3.3V rails.
The same goes for the low-frequency ripple. It is close to the permissible maximum on the +12V rail but weak on the other rails.
Temperature and Noise
Like its 1000W cousin, the Silent Pro M2 850W is cooled by an 11-blade 135mm Young Lin Tech DFS132512M fan which has a rated speed of 1500 RPM.
The start speed of the fan is below 700 RPM and doesn’t change until a load of 600 watts. Then the fan accelerates quickly but cannot reach even 1250 RPM over the remaining 200 watts. As a result, the Silent Pro M2 850W is a very quiet model in its class.
Efficiency and Power Factor
The Silent Pro M2 850W is 88.1%, 90.2% and 89% efficient at the reference loads of 20%, 50% and 100%. It thus meets even the 80 PLUS Gold requirements (and by a large margin, except at 50% load). The peak efficiency of 91.5% was observed at a load of 579 watts.
The power factor is in between 96 and 97% at high loads, which is somewhat lower than we usually get from PSUs with active power factor correction.
The standby source can easily cope with the specified loads.
The Silent Pro M2 850W features an original exterior design and excellent electrical parameters. It is very quiet, too. But its cable system isn’t optimal and the Taicon capacitors do not enjoy a good reputation among users.