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From: gillies@m.cs.uiuc.edu (Don Gillies)
Newsgroups: comp.sys.mac.hardware
Subject: Re: Leave the Mac on
Message-ID: <1991Feb28.050936.6830@m.cs.uiuc.edu>
Date: 28 Feb 91 05:09:36 GMT
References: <91053.130639DBG@SLACVM.SLAC.STANFORD.EDU>
Organization: University of Illinois, Dept. of Comp. Sci., Urbana, IL
Lines: 30

Re: leaving the Mac On.

As part of a UIUC campus energy audit, we recently contacted several
computer manufacturers (HP, IBM, Apollo) about whether it is a good
idea to leave their PC's turned on or to turn them off immediately
when not in use.

Every manufacturer contacted so far has said to TURN THEM OFF.  HP has
said that its burn-in testing process for PC's consists of cycling the
power on and off every second for 24 hours.

I think your "anecdotal" evidence is quite likely a crock of shit.
Disk drives fail because they are poorly manufactured.  You "seem" to
notice that they fail when the machines are turned off -- so what?
People who turn off their machines when not in use have them turned
off for at least 66% of their lifetime, so it is natural that the
disks would die when turned off.  Disks fail with old age and hard
use.

On the savings side, small PC's (mac SE, SE/030) consume 60 watts of
power and add to air conditioning (this facts were determined
empirically with electrical measuring devices).  Big PC's (Mac II, IBM
PS/2 50, 70) take more than 110 watts when turned on, and add to air
conditioning costs.  For a Mac II, at 8c/kilowatt, 66% wasted duty
cycle, that is 8c/day, $58 a year in wasted power (40-hour work week).
My Mac II has been cycled 2-3 times aday for 3.5 years with a
Quantum-80 disk drive, and never exhibited trouble.  And I'm not
counting the savings in air conditioning, etc.

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