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From: ajc@thendara.pa.dec.com (AJ Casamento)
Newsgroups: comp.unix.ultrix
Subject: Re: How to Cook a DECstation
Message-ID: <AJC.91Jun22104209@thendara.pa.dec.com>
Date: 22 Jun 91 16:42:09 GMT
References: <1991Jun21.182020.17142@raven.alaska.edu>
Sender: news@pa.dec.com (News)
Organization: Digital Equipment Corporation
Lines: 57
In-Reply-To: ddr@flux.isr.alaska.edu's message of 21 Jun 91 18:20:20 GMT


	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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