Yes it really is silent , have 2 and they make no noise , even when running full speed , 1575 rpm , it fits my no name mid tower case , it's 144mm tall so measure from top of cpu to side of case , if you have over 150 mm it will fit nicely .
Just don't use the paste it comes with , clean it off and use something good .
link to deepcool page , gives all measurements . They really have upped their game , bought 2 of their fans , 80 mm and 120mm the rubber coated frame ones , great quality , run silent and push lots of air , and they come with braided covers over the wires with many adapters .
http://deepcool-us.com/Product/GAMMAXX300/