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-...
(front of one of those cabinets, https://photos.smugmug.com/By-Date/2015/2015-01-31/n-vn7hn/i-cJs8Dkk/1/X3/i-...
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)