The reason it's loud is you need a fan to go up to just shy of 5,000 RPM's to keep it cool at default clock speeds in warm temperatures during the summer. If you under clock it, it will make it quieter because of less heat to contend with, which means less fan speed. Unless you have it working in warm climate. If you have several of them, you are better off putting them inside of something while keeping them cool to keep the noise down. Don't forget to get the heat out of the closure. That's the most important thing!
Don't try to run this rig at default clock speed of 2000 GH/s with fans that are lower RPM. Otherwise, it will run hot quite easily and possibly shut off periodically for reaching the 80 C threshold temperature depending on the ambient temperature they are sitting in.
That is my opinion. This rig just runs much hotter than the S3's.
So, basically, the only way to have these quieter is to run them at lower clock speeds in a room that does not have to high of an ambient temperature.