Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!zaphod.mps.ohio-state.edu!mips!sjsca4!poffen
From: poffen@sj.ate.slb.com (Russell Poffenberger)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Re: Leave the PC on vs. Power it off daily?
Message-ID: <1990Sep21.200033.17837@sj.ate.slb.com>
Date: 21 Sep 90 20:00:33 GMT
References: <1990Sep17.205845.12803@pdn.paradyne.com> <1480@ruunsa.fys.ruu.nl> <1990Sep19.144759.7880@watserv1.waterloo.edu>
Reply-To: poffen@sj.ate.slb.com (Russell Poffenberger)
Organization: Schlumberger Technologies, San Jose, CA.
Lines: 44

In article <1990Sep19.144759.7880@watserv1.waterloo.edu> ssingh@watserv1.waterloo.edu ($anjay [+] $ingh - Indy Studz) writes:
>In article <1480@ruunsa.fys.ruu.nl> chooft@ruunsa.fys.ruu.nl (Rob Hooft) writes:
>>In <1990Sep17.205845.12803@pdn.paradyne.com> dixon@pdn.paradyne.com 
>>(Tom Dixon) writes:
>>
>>>With todays pc hardware, exactly how dangerous is each power cycle?  
>>>If you power your office unit off every night, are you in for early 
>>>hardware failures?  Or is this all propaganda spread by electric power 
>>>companies?
>>
>>I run an XT since 17 feb 87, and upgraded with harddisk at 27 feb 87. This
>>machine is powered up and down at least once a day, usually more, at least
>>six days a week. I never had a problem.
>>
>>-- 
>>Rob Hooft, Chemistry department University of Utrecht.
>>hooft@hutruu54.bitnet hooft@chem.ruu.nl chooft@fys.ruu.nl
>
>We had a discussion on this topic some months ago on the net. The general
>concensus was that with the newer, better designed power supplies, it
>is okay to turn the machine off and on more often than once a day.
>
>Some years ago, it would have been smarter to leave your computer on
>all the time because the power supplies would allow such large surges
>through the machine on power-up.
>
>Unless the power supply is faulty to begin with, five years down the line,
>you will have moved up to a new computer with a new power supply to begin
>again with.
>
>

It isn't so much the power surges that can cause damage, but internal parts,
(especially CPU's) generate heat and run up to 50 degrees C (at junction)
hotter than room temperature. When you turn the system off, it cools down. Turn
it on, it heats up. This thermal cycling definitely DOES have a detrimental
effect on the part, mainly the package stresses and the lead bonding to the
die inside.


Russ Poffenberger               DOMAIN: poffen@sj.ate.slb.com
Schlumberger Technologies       UUCP:   {uunet,decwrl,amdahl}!sjsca4!poffen
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San Jose, Ca. 95110             (408)437-5254