With 6 case fans, a heat sync fan, at least 1 graphics card fan, and a PSU fan running... you may want to wear ear plugs. Pick the ones with the lowest noise level (dBA). And remember, all else being equal, the larger the fan diameter the quieter it will be.
Have any suggestions? I don't have much experience with case fans. Blue LED that has good air flow and is quite. 2 80mm and 4 120mm.