Quote Originally Posted by JohnGabriel View Post
Why is it we never see carbon filters or something in computer cases for dust?
Commodity cost model, plus liquid pressure ratings on common PC case fans, IMO. You see some limited filtering on higher-end models. Mine has removable fine-mesh screens over all of the ingress/egress points. Most inexpensive fans don't do static pressure well, like your common box fan -- it can move a lot of air when it gets things moving but if you seal off an end, it doesn't move resistant air the way a rotary impeller or centrifugal fan (aka squirrel cage blower) does. Noctua makes some really nice, reliable and fairly inexpensive fans targeted at the new liquid-cooling radiators and are designed with a significantly higher (in some cases almost double) static pressure rating. I replace both of the noisy, cheap-crap Corsair fans on my Hydro H81 with a single Noctua NF-12 and it runs cooler at idle and load while also being significantly quieter.