At 21:31 16/06/2005 -0400, you wrote: Hi Rich, Both of my 8800s have the fan blowing out. The general rule is: If the fan has a filter, then it should blow in.: By maintaining positive internal pressure, and filtering the air that comes in, you keep dust from entering the box. If it does not have a filter, it should blow out: A fast moving stream of air will carry more dust than a slow one. If you blow the fan in, it will carry dust into the box which will drop out before it exits at slower speed (because of the much larger area of all the vents and other openings) - it also causes dust buildup to concentrate that certain points bacause of sudden changes in airflow (you can often see bands of thick dust in boxes with fans improperly installed). Going the other way reduces the entry speed (same reason) and thus the amount of dust that enters - what does get in tends to settle out in a more uniform distribution. Regards, Dave -- dave04a (at) Dave Dunfield dunfield (dot) Firmware development services & tools: www.dunfield.com com Collector of vintage computing equipment: http://www.parse.com/~ddunfield/museum/index.html