When testing in a power supply laboratory it is difficult to take fan noise readings as the noise from the Sunmoon test equipment and air conditioning corrupts everything. The next best thing in our circumstances was reading off the fan speed with a tachometer to get an idea for the noise. The ambient temperature during testing held constant at 22 degrees, with 1 degree of variation. Each power supply had a consistent time period of 5 minutes to stabilise between each load scenario.
In my experience, the following general relationships apply between noise levels and fan speeds, though it can vary greatly between the type of fan used.
- Below 800 RPM – Inaudible/Silent
- 800 to 1000 RPM – Barely audible
- 1000 – 1200 RPM – Audible but still quiet
- 1200 – 1400 RPM – Moderately noisy
- 1400 – 1800 RPM – Noisy
- 1800 RPM or higher – Intolerable
The fan speed really didn’t want to do much of anything until it got past 80% load, however, at maximum the fan really did spin up quite a lot, but honestly wasn’t as noisy as we were expecting, easily on par with the 1200-1400 section of our scoring system.
The same results were to be found in Hybrid fan mode, albeit the 60% and below loads resulted in much lower or completely off fans speeds.