🚀 go-pugleaf

In article <1992Nov5.083110.7351@u.washington.edu> bketcham@stein.u.washington.edu (Benjamin Ketcham) writes:

>Well, I can't say I've done any tests on lifetime vs heat...
 
Although important I don't think CPU lifetime is the main issue here, I
think it's short term reliability.


>Everyone seems to agree that lower temperatures are in general better
>for semiconductors.  However, the question seems to be, does the decrease
>in CPU temp that these fans achieve really make any real difference?  I
>find it hard to believe that it does.  I have actually *never* seen a
>CPU fail in my relatively small personal sample of systems...


Well I quess your sample really has been small, or you've been very
lucky.  In the past 10 or 12 years I have seen numerous examples of
systems failing due to overheating; of course it's difficult to say if
it's actually the CPU, but keeping the silicon cool certainly cured
many of the situations.  

More recently and specificaly here at Olivetti we have several DX2 and
50Mhz 486's which run perfectly when cooled but stiff when not.  When
left running on the bench in free air the CPUs run at pretty close to
85C, ie. the maximum specified.  When running at 20ns cycle times it
doesn't take much extra heat to add a couple nanoseconds to some of
the internal critical paths, thus resulting in stopped CPU!


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Lots of deleted message....
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>Plus, nobody has considered the possibility that these fans might do
>more harm than good.  For one thing, as any service technician would
>agree, I'm sure, the biggest problem impacting system reliability is
>often the users opening the box up.  The chances of slipping with a
>screwdriver and doing major damage are probably orders of magnitude
>higher than the chances of a CPU failing within even 10 years.  What
>about the vibrations and electrical transients introduced by these
>fans?  Were any studies done about these factors?  After all, they are
>bonded right on top of the CPUs.  I would imagine that the CPU sockets
>are probably a good bit more susceptible to failure or intermittent
>noise problems, exacerbated by vibration, than the CPU itself.

I agree. 

However from our experiences most cases just don't have
sufficient airflow over the CPU to keep these new breeds of processors
within spec.  To solve this we have been fitting small 12V DC fans
blowing air dierctly over the CPU, this results in about a 20C
reduction in CPU case temperature.  It doesn't add any height, there's
no mechanical stress etc.  There are lots of fans available about 60
or 80 mm square, try Radio Shack, they are probably also cheaper than
any of the various 'koolers' on sale.

So Ben, in short we have first hand experience of CPUs stiffing due to
overheating, and directed cooling solves the problem.

How about someone from Intel giving us the long term reliability