Found this on my heatsink today!!!
after i cleaned it, my temperatures dropped from 35 idle and 47 load to 29 idle and 36 load. I guess with the 120 CFM of the 92 mm tornado on it, comes a lot of dust
http://www.u-fess.netfirms.com/Page 1.htm
http://www.u-fess.netfirms.com/Page 1.htm