last revised Oct 2 2000

Denoising the Hardware

The industries' apparent inability to produce quiet PCs has led me to think about denoising measures myself.
Sometimes I'm reminiscing the olden days of the C64, when computers were quiet and booted instantly...

There are three main sources of noise: the power supply fan, the CPU fan and the hard disk(s).
Other sources like video board fans and CDRom drives can easily be overcome by choosing the appropriate components.
In my case I chose to use a relatively old video board (Hercules Thriller, 4MB), that doesn't have a fan but still has moderate 3D abilities for the occasional game.
My CD Rom drive is a TEAC CD524 24-speed model that's fast enough for anything I ever used it for (especially audio extraction is very good - up to 16*), but still relatively quiet.
Recently I installed a 48* drive in a friend's computer - no way I will ever use any of those beasts. At full bore this thing sounds like a jet during takeoff.

- The power supply fan.

Measures include a temperature controlled speed regulator (Circuit diagram) which keeps the fan speed to an absolute minimum and the inner case temperature to approx. 35° Celsius.

- The CPU fan.

I have added a large heat sink and a temperature controlled speed regulator which shuts off the fan completely below CPU temperatures of approx. 55° Celsius. Details and circuit diagram here.
Above 55° the fan speeds up to keep a maximum temperature of approx. 60° under full load (running setiathome, for example).

- The hard disk(s).

My philosophy is to use quiet drives to begin with. Although I am using two drives currently, I will repartition them to use one (the faster 8GB Fujitsu) as the main drive and the smaller one (4GB Fujitsu) for seldom accessed data only. This way I can use the BIOS powerdown feature and have only one drive running most of the time.
There are some suppliers that offer denoising cages and the like, but currently I can't use those because they need a 5,25" Slot which I can't spare in my Midi Tower.


All of these measures have reduced the noise by approximately 5dB, but it's still not enough. I want a computer that does it's thing without constantly reminding me of it's existence...
Probably one day I have to design a power supply and a case that work with passive cooling only.