babuganoosh

Well having annoying fans is really annoying when you doing work and trying to concentrate on doing something. Once you experience a full silent PC you will never go back.   

What is your current CPU? both of the cooler is overkill for most cpu. 
 
edit: i have NH-D15 it really not even hearable at idle and even at load if you wearing a headphones you should be fine, the noise is not annoying either. It OC really well but you need to watch your voltages you should run fan as these coolers aren't passive towers.  

Both coolers are good, especially the NH-D15, which has performance similar to an AIO liquid cooler and is silent. The intel stock cooler's fan can be controlled to keep noise levels down, but can be a bit too noisy for your liking when the pc is under load.

No rule you must run whatever default fan profile the BIOS throws at you. As long as the CPU temp isn't outside your preference range. You can lower the fan speed. In 400-500rpm, you can't hear any noise even if you try. But the fan still pushes some air and keep the CPU in safe temperature when idling, instead of going all out to run it fanless.