"Johannes H Andersen" wrote:

Then you have cut out reflections of noise from the wall.


Yes. The intention is to keep the noise from getting to
one's ears, not from keeping within the tower.


It's OK if you can remove noise by some simple means.
It is unfortunate that the cabinet sometimes amplifies the noise,


That is one purpose of the carpeting - to damp out vibrations
of the cabinet walls. Cheap foamed-backed stick-on
carpeting squares would be perfect for this.


I've found that opening the cabinet on my PC actually reduces
the noise, but then it diverts the airflow which you don't particularly
want.


If you leave a 6-inch clearance in the back and a 3-inch
clearance in the front, the interference in air flow will be
negligible. Remember that both the rear and the front walls
of the cabinet do not contact the desk or the floor of the
cabinet but leave large gaps for air flow.


Hence there are acoustic considerations as well. I have tried
to shield my PC with a plywood box, but it gave little result


Try it again with carpeting lining the inner surfaces.


and access was cumbersome if I wanted to do something.


An access door in the front, and that 6-inch clearance
at the back would help with that.


Instead I now have a good CPU heat sink with temperature
control (the CPU fan rarely runs) plus a 50 Ohm 3 Watts
resistor in series with the PSU fan. The PSU fan resistor was
carefully chosen by feeling the temperature of the PSU components.


Yes, my fingers are the calibrated type, too. :-)
But you must remember that the PSU fan contributes
to the overall air flow in the tower, and if it has an intake
on its bottom wall, it helps to ventillate the CPU.


*TimDaniels*