OCModShop has posted a review of the Danger Den D4 watercooling pump

The amount of noise from a pump is somewhat of a subjective factor but noise can make a pump intolerable regardless of the pump's performance. While dBA meters can provide a number for the raw volume of pumps, fans, etc., the tone and pitch of the sound is usually what determines whether or not the part is considered loud or annoying. Watercooling pumps can make a variety of annoying sounds such as impeller ticking or clicking, humming, vibrations noises, as well as others. So, how does all of this apply to the DD4?

Danger Den D4 watercooling pump review