On 12/24/2016 5:24 PM, geo.inbox.ignored wrote: > temperature regulated fan speed can reduce noise. > > use of a baffle box with styrofoam or thin foam rubber lining. > > -----+-----+ > fan \/ | | > /\ | | > --+-----+--- > ^ ^ > baffles > > spacing between upper and lower baffles must be equal to or larger > than diameter of fan so as to not restrict flow. also, making > enclosure 2" larger than fan will help reduce restriction. he said 'server rack'. thats a probably 6' tall cabinet filled with servers, each of which has likely dozens of high speed fans. (back of 2 server cabinets I used to run at work...) https://photos.smugmug.com/By-Date/2015/2015-01-31/n-vn7hn/i-QFKg46V/0/X3/i-QFKg46V-X3.jpg (front of one of those cabinets, https://photos.smugmug.com/By-Date/2015/2015-01-31/n-vn7hn/i-cJs8Dkk/1/X3/i-cJs8Dkk-X3.jpg a cabinet like that needs 600 cubic feet/minute or more airflow. now, I'm guessing that H's rack isn't quite this big, or as densely populated, since its not in a dedicated server room, but still, it has a lot more than a couple fans to silence. my rack there has 8 servers, 2 additional disk trays, and about 200 disk drives, also a pair of 7000 VA UPS's in the bottom (actual load was around 3000VA) -- john r pierce, recycling bits in santa cruz
