In article <2181@fnnews.fnal.gov> rohrer@fncrd6.fnal.gov (Keith Rohrer) writes:
quoted text
>In article <1992Aug14.083358.24246@news.th-darmstadt.de> herr@iti.informatik.th-darmstadt.de (Gabor Herr) writes:
>>In article <1992Aug13.130554.14600@crd.ge.com>, davidsen@ariel.crd.GE.COM (william E Davidsen) writes:
>[deleted]
>>because these two chips were the only ones getting hot. And there was another
>>cooling effect too: after I was tired of removing and installing the boards in my
>I've discovered that, even with a case that has incredibly poor ventilation,
>the hard drive and (if the CPU is a hot one) the CPU will be cooler if you
>close the case and allow the fan to draw air across them than if you just
>leave the case open and let normal air currents try to cool it.
>While I was working on my new 386-40 motherboard, within an hour of
>use with the case open, the chip got so hot it burned my finger to touch
>it.  But I could leave the machine on for hours with the cover on,
>and the CPU only got too hot to touch for more than a second or two.
>I think I may have also cooked a hard drive running it with the cover off
>the (main) case.

PCs are designed to run with the case on, drawing air across the chips
because forced convection is _*much*_ more efficient than normal
convection. As a result, running the machine with the case open will
likely cook the chips after ahwile, and tower case PCs have a second set
of fans (my Northgate has a pair of fans which blow directly across the 
motherboard; the end slots for the full-length boards are mounted on the
fan casings (ie, the fans blow across the daughterboards as well)).
In other words, running your PC for extended periods of time is a 
Bad Thing to Be Avoided(TM).
If it _is_ a problem with the AMD chips, it's only on their 40Mhz chips;
I have a bulding full of PCs with AMD386 processors, and not a one of them
has given me any trouble. Including the AMD386DX-33 in my machine (which
has run everything from Linux to OS/2 2.0 to NetWare 3.11).

                                James

James P. Callison       Microcomputer Coordinator        OU Law Library 
Callison@aardvark.ucs.uoknor.edu   /\        Callison@uokmax.ecn.uoknor
        constellation!biglaw!callison@mailhost.ecn.uoknor.edu
DISCLAIMER: I'm not an engineer, but I play one at work...
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        To those who stand on empty shores, and spit against the wind
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