[sdiy] OT: The best ways to silence a PC?

[Magnus Danielson]

From: Peter Grenader <petergrenader at mksound.com>
Subject: Re: [sdiy] OT: The best ways to silence a PC?
Date: Sat, 10 May 2003 03:57:44 -0600

> Now, this was like 20 drives - but the vents on your machine are there for a
> reason.  Without them, you might as well disconnect the fan because at that
> point, all it's doing is contributing to the heat.

AND NOISE!

In a PC usually only two out of three noise sources is discussed. The noise of
the fans themselfs and the noise of the drives (hard-disk, floppy and
CDs/DVDs), i.e. the mechanical devices in the PC. Then you have the noise of
the airflow, the turbulent airstreams (such as air slipping over an edge of
some sort) will also contribute to the total noise.

If you have bad venting that will cause turbolence and hence noise.
If your airstream walks over a messedup landscape iy will cause turbolence and
hence noise.

So, for best result should the airflow be guided from inside to outside in an
as smooth path as possible. Possibly with specially made guideance walls to
make sure the flow goes the right way.

As for mechanical devices (fans and drives) you have to watch out since they
will emitt energy both through straight acoustical emission into air, but more
importantly into the chassi itself. For best result you should make sure that
you dampen the transmission path of these vibrations as soon as possible. Here
cables can be a headache, for a drive shaking in it's siliconrubber damping can
emitt vibrations through cables, so a streched cable will now conduct
vibrations to the other end (and while at it probably age quicker!) so all
cables to suspended mechanical devices should have an unstreched slack.

Then for vibrations you might do something about those big membrane things
called sides. Damping them can help. Be sure not to invent a new problem by
accidentially retune their resonance frequency so you hit one of the vibration
frequencies. One of the things you want is really real damping, i.e. vibration
to heat conversions, so that the vibrational energy is lost even at resonance
frequencies.

Tighten something up can work for and against you. You want to make sure you
short vibration out. Somethimes things are better floating around in suspension
then having it tight. Don't forget that there is a DC property of the full
enclosure, you want static forces still applied in order for the box still to
hold together as one device...

As for fans, smaller fans needs higher speeds to pump the same about of air
per time unit than larger fans. This forces the higher speed of outer edge and
higher noise due to turbolence. Good fans are made to reduce that.

You might consider changing type of fan even.

Happy damping!

Cheers,
Magnus