D-Link DNS-323 FAN modification. Sorry for the quality :)

ondro727

Back plate - fan protection cut out, opening enlarged (so it does not partially cover edges of the fan) and edges rounded
Padding - some additional foam added between back plate and inner construcion to eliminate "dull echoing sound", after backplate is attached (there is a small empty space between backplate and construction, which works as a "resonance amplifier", so the aim is to minimize this)
Closed - final assembly, no edges in the way of airflow :) MUCH more quiet, at least in my case... I can barely hear the fan now.