We measure from a distance of around 1 meter from the closed chassis and 4 foot from the ground to mirror a real world situation. Ambient noise in the room measures close to the limits of our sound meter at 30dBa.
The minimum readings for our acoustics tests are obtained with the fans running at 5V. For our maximum readings the fans were left running at 12V. The CPU and GPU fans are manually disconnected to eliminate unwanted noise.
KitGuru noise guide
10dBA – Normal Breathing/Rustling Leaves
20-25dBA – Whisper
30dBA – High Quality Computer fan
40dBA – A Bubbling Brook, or a Refridgerator
50dBA – Normal Conversation
60dBA – Laughter
70dBA – Vacuum Cleaner or Hairdryer
80dBA – City Traffic or a Garbage Disposal
90dBA – Motorcycle or Lawnmower
100dBA – MP3 player at maximum output
110dBA – Orchestra
120dBA – Front row rock concert/Jet Engine
130dBA – Threshold of Pain
140dBA – Military Jet takeoff/Gunshot (close range)
160dBA – Instant Perforation of eardrum
Running at 5V the fans produce only minimal noise. At 12V this increases to 38.4dBa. This makes the fans noticeable but not overly loud. All in all, the use of two strategically placed fans helps to keep noise levels in check.