# 61848 Leave Computer On or Off ?
Response Number 10
Name: Blazer
Date: January 24, 2001 at 11:18:43 Pacific
Subject: To turn off computer or not!
Reply:
This question always gets more responses than it deserves . I mostly leave mine on with maximum powerdown after a specified time.
This is one is an interesting response :
Turning a machine on and off frequently
has a side effect called thermal cycling.
Components heating up and cooling down is
said to be one of the largest contributors
to component failure. I have seen unsecured
boards "creep" up out of their slots and burn out board and slot.
Also see:
http://www.lcsc.edu/it/computer_shutdown.htm
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Response Number 11
Name: Heather Braun
Date: January 24, 2001 at 11:21:58 Pacific
Homepage: Consciousness Beholding All
Subject: To turn off computer or not!
Reply:
Thanks everyone...I appreciate the input! So basically...still two points of view.
Larry sent me an email with the following info:
The PC power question boils down to wearing out components by leaving the
system on versus jolting the system with electricity through frequent on and
off cycles. The biggest stress on any electrical system is turning it on.
Bruce Drenning, network engineer for DPSC Technology Consultants, says
turning on any electrical appliance produces an initial electrical spike
that is generally three times higher than the amount of electricity needed
to power the appliance. You've witnessed this phenomenon if the lights in
your home ever dimmed when you turned on a hair dryer. Light bulbs tend to
blow with that initial spike of electricity produced when you turn them on.
The more frequently you flip the switch on and off, the shorter the bulb's
life. Leaving it on all the time protects the bulb from that spike, but it
will still eventually burn out. The same is true of your PC, which tends to
be particularly sensitive to that initial electrical spike.
Thermal stress is another startup problem for your PC and another good
reason to leave it on. When the PC comes on, the components heat up and
expand. When turned off, they cool down and contract. This cycle of thermal
stress is more detrimental to the life span of your PC and is more of an
immediate threat than the individual components wearing out. Another school
of thought says that the parts wear out anyway, so there is no reason to
waste electricity by leaving your PC on all the time. Steven Koch, technical
services engineer with Sony, advises keeping damage from the initial power
surge in perspective. Jostling your computer in a move, smoking around it,
and dropping it are all far more damaging than turning it off and on, he
says.
Monitoring Power.
While there's no general consensus on PCs, manufacturers and technical
support people say if you plan to leave your monitor for more than two
hours, you should turn it off or put it in sleep mode. This special setting
leaves the monitor on in a low power mode. Newer operating systems let you
program how long your monitor can be left unattended before "going to
sleep."
A monitor running at full power consumes nearly as much power as a PC, which
can significantly increase your electric bill. Figures vary considerably,
but monitors in use can consume 80 to 150 watts. Most monitors we checked
drew 8 to 15 watts in sleep mode. Turning off the monitor doesn't
necessarily stop the drawing of power altogether. Any appliance with a
memory setting and no battery backup will continue to draw 3 to 8 watts even
when turned off. Monitors that let you set the screen width, for example,
will preserve that setting when they're off, but to do it they need power.
Without this feature, you have to reset the monitor each time you turn it
on. Koch says the amount of power monitors draw is such a concern in the
industry that Sony is working on a monitor with a zero watt switch. The
monitor draws close to zero watts and is as close to unplugging it as you
can get without actually pulling the plug.
Power saving features similar to these are a key feature in green PCs. The
housing and internal components of these PCs are built with recyclable
materials. Features such as low energy sleep modes let green PCs run
constantly with a negligible effect on electric bills. Smart monitors, which
meet the guidelines set by the Video/Electronic Standards Association
(VESA), have four stages in which the monitor gradually uses less power.
These monitors can be programmed through operating systems that comply with
Display Power Management Signaling (DPMS) standards. The first DPMS stage is
on and functioning - either the monitor is in use or the screen saver is
engaged. In this stage, the monitor draws peak power. In the standby stage,
the monitor draws 50% less power and offers a fast reaction to input; it
responds almost immediately to mouse movement. In the suspend (or sleep)
stage, the picture tube is actually off, and the monitor draws 10 to 15
watts.
To get out of suspend, you must press the PC's wake-up or sleep button.
Because the picture tube was off, the monitor will slowly grow brighter just
as it does when you first power up for the day. The final stage is off, but
the monitor has not been physically switched off by the user. The circuitry
is still active, and the monitor is drawing 3 to 7 watts. Newer
Windows-based operating systems offer the configurations that determine how
much time elapses before the monitor gradually powers down.
If your monitor lacks the power-down features outlined above, the easiest
way to prolong its life is to turn it off each day. Monitors are subject to
thermal stress, but the life span of a monitor is inversely related to the
amount of time it is on. The longer it's on, the shorter its life span.
Young Bae, product manager for CTX International, says monitors are far less
sensitive to the power spike than PCs, and the secret to monitor longevity
is turning it off daily. You should also turn your monitor off or put it in
sleep mode because phosphor, the chemical lining in the tube in your
monitor, has a limited life. When the screen is on, the phosphor glows to
produce the on-screen image. Years ago a static image on the screen would
bum itself permanently into the phosphor, producing persistent "ghost"
images. Monitor makers warned us to keep the images moving on the screen or
shut off the monitor. Although burn-in technically is still possible, Koch
laughingly says that the image would have to be on your screen for about 12
years before burning in! Monitors have a finite amount of phosphor, however,
and as the monitor ages, the phosphor grows dimmer and dimmer. You will
enhance the life of the phosphor significantly by putting the monitor in
sleep mode, using a darkened screen saver, or turning the monitor off when
it is not in use.
Which Comes First?
If you turn off your PC, monitor, and other hardware such as printers and
scanners every day, several monitor manufacturers suggest turning on the
monitor first when you restart everything. Bae explains that the PC's
operating system will query the monitor about its identity, and it's
possible that the operating system won't interface properly with the monitor
if it can't find it during the initial search. That is a rare problem, but
you can avoid the possibility by turning on your monitor first. Koch says
one Sony system specifically requires that the computer be turned on first,
but with most systems, you may turn on the monitor first.
Many users want to power up and power down their PCs and related hardware
with a single switch. Manufacturers and technicians we interviewed agreed
that shutting off the entire configuration at the power strip isn't a
problem as long as you follow the shutdown procedure for your operating
system.
Operating System.
That software step is a critical one for any system shutdown. Failing to
shut down the operating system can damage files and produce a long delay
when you turn on your PC again. The wait will be similar to the delay
experienced when you restart the PC after an abrupt loss of power, which is
essentially what your operating system suffers when shut down improperly. To
do things right, click the Start button in Windows 95 and choose Shut Down.
In Windows 3.1, choose Exit Windows from Program Manager's File menu.
Even if you regularly put your computer to sleep or leave it on, Drenning
advises shutting down and restarting the operating system regularly. The
longer you go without rebooting (restarting), the more likely a crash
becomes. Your PC regularly creates temporary files while running. These
files are normally discarded when you shut down the operating system, but if
you never reboot, the temporary files get huge, and the entire system will
run sluggishly. Drenning advises performing a warm reboot once a day, and,
at minimum, once every three days to clear the cache (memory that stores
frequently used data) and regular memory. A warm reboot occurs when you push
the Reset button on the PC's case or restart the operating system without
shutting off the PC. A cold reboot involves physically turning off the PC.
Another kind of software shutdown is important for PCs connected to a
network. Network users probably log out at the end of each day, if not turn
off the system entirely. Dr. Mark Misic, director of information systems &
communication services for the College of Business at Northern Illinois
University, says server software (which runs a network) cannot be upgraded
when individual users are online and using it. Just think of the problems
that could arise if you tried upgrading software on your PC while using the
application.
Individuals who leave applications open during a network hardware change
cause problems for the server itself. Before a network hardware change, a
complete backup of everything on the server is necessary. If individual
users have files open at the time of the backup, it's possible that the
server won't read or back up the open file, or the server may simply hang up
at that point. The choices for network users are obviously more restrictive
than those for users of single PCs. On your desk, the only real shut down
requirement is to regularly restart the operating system to avoid crashes
and sluggish performance. You have the power to make your own policy on the
other power questions.
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Response Number 12
Name: Blazer
Date: January 24, 2001 at 15:19:20 Pacific
Subject: To turn off computer or not!
Reply:
Although lengthy , Heather answering her own question is the best coverage I've seen on this issue in this forum and I will keep it for future reference. Ole'
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