In our noise level tests we switched off all the case fans and replaced the AMD Radeon HD 7950 graphics card with a HD 5550 passive model so were just taking into account the noise generated by the fans themselves. We measured the noise level with a Digital Noise Level meter at a distance of 1m from the front of the case.
The H80i also performed well in this test. It as inaudible in quiet mode and the noise level only increased slightly with balanced mode activated. In performance mode it was fairly loud but not intrusive and with the fans set to maximum, the was deafeningly loud.