It choked on a wad of cat hair. In retrospect, this explains why my cpu temps were soaring over 80C and the box was amazingly quiet. So I remove the fan guard and extract the 80mm fan thinking this was a 5 minute job. But wait, its not the standard 25mm thick, its only 15mm or so. Crap. So far all my searching has failed to enlighten me as to where a fan of such proportions might be purchased. Any suggestions?