The Silverstone Zeus 850w was placed under a load of 646 watts. This counts for a total of 76% of the power supplies rated output. At this load, the power supply required 786 watts from the mains to produce the 646 watts required by our custom made power supply tester.
Therefore the efficiency of this power supply can be found by a simple equation: (646 / 786) * 100 that works out to be an efficiency rating of 82.1%.Noise Testing
At present Overclock3D doesn't have the professional equipment required to reliably measure the noise output of devices. However, as a new part of our testing procedure we will be recording the PSU at idle and load so that you can make your own judgments. All recordings are taken at 30cm distance from the unit.
Idle Recording - Download
Load Recording - Download
As previously stated, the ST85ZF utilises a Sanyo Denki San Cooler 80mm fan, which pushes a 42cfm at 34dBA when running at full speed. Thankfully Silverstone have implemented a fan speed controller that adjusts the RPM based on the temperature of the unit.
Under idle conditions the fan speed was significantly throttled. This meant that all that could be heard was the whisper of air moving around the unit. With the ST85ZF installed inside a case, I was unable to hear the unit at all.
When placed under load, the ST85ZF gradually increased the fan speed to counteract the heat. As you can hear from the recording above, the ST85ZF was quite noisy. However, with the ST85ZF installed inside a case, the noise levels were much more reasonable.