Ambient noise in the room is around 20-25dBa. We measure from a distance of around 1,5 meters from the closed chassis and 4 foot from the ground to mirror a real world situation.
We use a calibrated meter.
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
The system is very quiet when idle, but becomes clearly audible under gaming load. Surprisingly it isn't as loud as I had initially considered it might be. Overclockers UK have spaced the R9 295X2 cards apart to allow for airflow between the cards, which helps a little.