How to Cook a DECstation
AJ Casamento
ajc at thendara.pa.dec.com
Sun Jun 23 02:42:09 AEST 1991
Don,
As Jim Gettys has already pointed out, the system boxes on our
DS5000/xxx machines have thermostatically controlled fans. This
allows them to speed up when the temperature in the box gets higher.
It also allows them to run very slowly/quietly when they are not
needed. However, I posted your inquiry to the Reliability Engineers
just out of curiousity, and Jim was also correct in that we really
do mean what the specifications say.
To paraphrase my colleagues, and with NO intent to imply any
warranty other than that explicitly in the documentation that is
provided with the system (ie. this discussion is ONLY that, just
a discussion):
* The DS5000/xxx reliability numbers are generated at a target of
25 C but are verified at 40 C.
* While the system will probably crash at ~50 C (122 F) it is not
likely that the componenets will be permanently damaged below
~55 C (131 F).
* The other potential for generating such damage is if you block
the ventilation of the system (say by placing it on it's side
or putting books along it).
* For the system to be in danger of catching fire, it would have
to be heated to well over 200 C (400 F). The plastics in the
system box, keyboard and monitor are flame retardent and are
not intended to support combustion once the flame has been removed
(ie. if you hold a torch to it you can make it burn, but if you
take the torch away, the flames should go out).
While I am not a reliability engineer myself, I would be surprised
if the MTBF numbers (Mean Time Between Failures) remains constant
when the machine is run at 40 C on a continual basis. That is why
ruggedized versions of the systems are made, to support the application
needs of industrial/military systems.
So, if I've bored you enough, I hope this information satisfies
your curiousity.
Thanx,
AJ
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* AJ Casamento "The question is not whether or *
* Digital's TRI/ADD Program not the opinions are mine; but *
* 100 Hamilton Ave. UCO1-B rather, which of my personalities *
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* 415.853.6744 *
* ajc at decwrl.dec.com *
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