Sound level - whistler or noise?
The noise of a cooler during operation is an important aspect. This is depending on the friction and the air flow. The unit for "noise" is decibel dBA. Note that the scale is logarithmic. A difference of 10 dBA means that it is two times louder!
We ran our noise tests in our sound chamber using a sound level meter. The following two pictures show the test methodology.
Our miniature sound chamber has enough space for a motherboard, hard disk or even a CPU cooler. The noise level is determined in the middle above the CPU cooler at a constant distance.
The power supply is located outside the box and is steadily monitored.