The output voltages are very stable. The +3.3V voltage is the only one to get red at maximum load. None of the three tracked voltages goes out of the allowable range in any point of the diagram.
The output voltage ripple is about 45 millivolts on each output line at max load. This is within the allowable limit.
The ET850 employs a Sanyo Denki fan (San Cooler 80 9A0182S402). Its rated speed is 3400rpm. Located at the back of the PSU, this fan is going to be inside the system case in an assembled PC. This should make the whole system less noisy. The efficiency of cooling is not affected: the PSU has vent holes in its front and rear panels only, and the direction of airflow doesn’t depend on the position of the fan.
The PSU proved to have an extremely high operating temperature in my tests, however. The difference between the input and output air temperature was over 25°C while the fan only sped up to 2700rpm. Moreover, I tested the PSU on the next day when it was rather hot in our test lab – about 26°C – and the PSU shut down when working at full output power and could only start up again in ten minutes.
I don’t understand this behavior. The fan controller should have made the fan work at the maximum possible speed at such high temperatures or the manufacturer should have installed a more powerful fan. I can only hope I tested a defective sample.
The efficiency is 83% at the maximum and generally higher than 80%. These numbers are good, but not impressive anymore against modern models with an efficiency of 85% and higher. The power factor is near 1.0 – the active PFC device does its job well.
So, the Etasis ET850 is a good power supply with an original circuit design solution and superb electrical parameters but with one drawback. Its fan controller did not make the fan rotate at full speed and the PSU would overheat under max load. An interesting fact, being very similar to the ET850 in its internal design, the SilverStone Zeus SST-ST85ZF didn’t have that problem. Its fan would speed up to 3400rpm at a load of 700W.