[X4U] Leaving an iMac running 24/7

[Randy B.Singer]

John Richardson said:

>Is there any downside to running an iMac G5 20" all the time?


This is a subject that has been debated many times.

The guru for my old Mac User Group, BMUG, called a number of Apple 
engineers to settle this question.  The answer was that, while business 
mainframe computers are meant to be left on all the time, personal 
computers aren't built to the same standards (and hence cost a lot less) 
and live longer if you shut them down when you will not be using them for 
an extended period, let's say about an hour or more.

There are exceptions.  Some Macs that don't have fans can suffer from the 
continued heat cycling caused by frequently turning them on and off, and 
can develop cold solder joints.  (I've fixed many Mac Pluses just by 
touching the solder joints around the flyback with a soldering pen.  In 
fact, I used to install fans in Mac Pluses for friends to make them last 
longer.)

And a Mac whose hard drive is obviously on its last legs should not be 
turned off until the drive is fully backed up.  Drives that are about to 
die commonly give up on startup.

A number of years ago Macworld put to the test the old myth that turning 
a Mac on and off caused surges that eventually would lead to the 
machine's death.  Their testing showed that Macs had an impressive amount 
of surge protection built in, and that turning them on and off was not a 
problem at all.  It helps to use a good (not cheap) UPS with automatic 
voltage regulation (AVR). 

Hard drives and other components can wear out if left running 
continually. LCD monitors will lose their brightness and can eventually 
need an expensive replacement of the backlight.

And, of course, shutting down your Mac overnight saves energy. 

Depending on how long you are expecting your Mac to last, it may not make 
a big difference one way or another.  Most folks don't expect their 
personal computer to last more than about 5 years these days, before they 
are longing for a newer, faster, better one.



Randy B. Singer
Co-Author of: The Macintosh Bible (4th, 5th and 6th editions)

Routine OS X Maintenance and Generic Troubleshooting
http://www.macattorney.com/ts.html