If you really want to research the hell out of it, start here:
http://www.silentpcreview.com/forums/ and
http://www.silentpcreview.com/
PS, don't use case like mine if your ultimate goal is silence. While it works great and is still considered quiet, mine has a mesh sidewall that allows some sound to transfer outside. Tons of reviews and first hand experience for both cases and fans on the above sites. Lots of factors and options to consider.