Best way I know of to have a quiet system is to have the speed of case fans controlled the same as CPU and GPU. Idle at 6-800rpm when system is idle or low load. Speed up to supply air as needed.. Rarely done until a couple years ago but is becoming more common all the time. First link in my sig explains how I do it.
We will be able to use 3-pin voltage controlled fans once Phanteks releases their PWM controlled 3pin fan hub as an accessory. Now it is only supplied with Enthoo Primo case.
What is your system? Case, CPU cooler, GPU, fan configuration, etc.