First of all what kinda case you got?
And what size fanhole?
I suggest first 1 or 2 quiet case fans. Remember, its better to have alittle flow in your case rather then more airflow on your cpu cooler.
For quiet I like this one for 120mm:
Yate Loon D12SL
If your still not satisfied with this already quiet fan, then do what I did, Pair it up with a nice fancontroller:
Sunbeam Rheobus
And for the cpu cooler these are my favorites for quiet:
Thermalright Ultra 120
^You will need a additional fan of your choice
Scythe Mine
That sonic tower is also a very quiet heatsink if paired with the right fan.