To conduct our noise level tests, we replaced the graphics card in our system with a AMD Radeon HD 5550 Silence which was passively cooled. We also momentarily disconnected the fans on the CPU cooler so we were only taking into account the noise generated by the fans in the case.
We can see that even with the fans at full speed the case remains pretty quiet. Those looking to build a very quiet system should invest in some ultra quiet fans, though, as the included ones aren't exactly silent.
Excellent review!