[geeks] Quieting a Netra T1 AC200?

[Phil Stracchino]

Lionel Peterson wrote:
> Same size, same airflow yields same noise, right?

Not necessarily.  In the same size and airflow you can find huge
differences in noise level.  Blade count and design, bearing type,
housing design, all affect the noise level.  Many fans are just made to
be cheap for a specified airflow without any particular attention to
being quiet.

> Phil mentioned in an
> earlier posting that he went down in airflow, almost same size and
> reduced noise considerably.
> 
> Exact replacements will reduce the noise of a failing fan.

As was the case in my 1U case, I'm pretty sure.  The two fans I replaced
were both running a good 10dBA louder than they should have been.
Remember, every 3dBA is a doubling of human perceived noise level.  When
a previously quiet fan starts whining, rattling or screeching, it's a
clear warning sign that its bearings are shot.

Because I had an open fan slot to add an extra fan, I was able to
replace two failing fans with three good ones and cut about 20dBA with
no significant net loss of airflow.  (I lost about 3cfm ... I replaced
two 9200rpm 17cfm fans with three 5400rpm 10.5cfm ones.)


-- 
  Phil Stracchino, CDK#2     DoD#299792458     ICBM: 43.5607, -71.355
  alaric at caerllewys.net   alaric at metrocast.net   phil at co.ordinate.org
         Renaissance Man, Unix ronin, Perl hacker, Free Stater
                 It's not the years, it's the mileage.