[Beowulf] Not all cases need be metal

Nifty niftyompi Mitch niftyompi at niftyegg.com
Thu Oct 30 01:21:48 EDT 2008


On Fri, Oct 24, 2008 at 12:05:24AM -0400, Sebastian Hyde wrote:
> 
> http://www.instructables.com/id/Lexan-Computer-Case/
> 

It should be noted that a safety certifications for computer
systems pay attention to the vertical flame rating of all the material
inside the chassis and the chassis itself.  i.e. the ability of the material
to sustain a fire.

Another agency certification involves radio frequency emissions.
In general the radio frequency emissions (in the US FCC part 15)
all but forces computers to live in a Faraday cage (metal box).

The radio frequency interference issues with modern hardware have moved
way up frequency with today's high speed clocks.  The common issues
are bad cell phone reception, bad WiFI and other stuff.  If you sell a
product you must measure and comply.   Big iron, like the early Crays,
often did on site RF measurements and testing at the customers site.

The Fire hazard risk should NOT be ignored!
 
Lexan can be made with fire retardants in it to 
improve its good properties in this regard.   But I doubt
it is equal to a metal chassis.   If you inspect the 
motherboard you will find an agency symbol that reflects
the fire rating of the PCB material.  If you sell a product
and want to be insured you need to pay attention.  In some 
cities and countries a safety evaluation is not optional!

Power level at the wall changes the rules.  The more power the
more will be required for UL and VDE compliance.

To some degree an individual has some wiggle room that a company 
does not have.   However if you are building a "supercomputer" 
in space you do not own "you will comply"  ;-).

If I recall the early Google racks were "open frame" designs.
It is possible to do some interesting things 'out of the box',
as it were.


-- 
	T o m  M i t c h e l l 
	Found me a new hat, now what?
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