I was disappointed with the noise level of my Noctua D15, so I removed one of the fans. Removing one fan has far more than halved the noise level so they must have somehow interfered with each other to cause more noise together than the sum of both individually.
I replaced my already quite Corsair exhaust fan with the spare Noctua. Now almost total silence.
I replaced my already quite Corsair exhaust fan with the spare Noctua. Now almost total silence.