Your Computer Cant Keep Time

By: Stephen Bucaro

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Your Computer Can't Keep Time

By Stephen Bucaro

A computer needs a certain amount of information to
operate; for example, the date and time, the amount of
memory installed, the number of drives and their
configuration, and so on. In the early days of computers,
either the user typed in this information each time the
computer started, or it was set using DIP switches and
jumpers. Today, computers store this information in a CMOS
chip that uses a small battery to retain the information
when the computer is shut off.

CMOS (complementary metal oxide semiconductor) is type of
chip that consumes very little power; therefore, while the
computer is turned off, the battery discharges very slowly. But
the battery will totally discharge if you leave your
computer turned off for a year or so. Even if you turn
your computer on every day, the battery is designed to
last only a couple of years. Occasionally a battery will
fail prematurely.

Today's plug-and-play computers can detect most of the
necessary settings, but if your CMOS battery is dead, your
computer will not be able to retain the date and time.

computer will also lose any custom settings, for example,
the boot sequence. If you set a password in CMOS, you may
be locked out of the computer. If the CMOS battery does fail,
you might receive the message "System Configuration Lost"
when you start the computer. It would be wise to record all
the CMOS settings as a precaution.

To record the CMOS settings, watch for an on-screen prompt
when you first start your computer. The prompt tells you to
press a key, usually the Del or F2, to enter CMOS. To enter
the CMOS configuration utility, you have to press the
indicated key while the message is on the screen. After the
CMOS configuration screen appears, follow the instructions
provided to page through all the screens and record all the

If your computer loses its time setting overnight, the CMOS
battery may not be holding a charge. The CMOS battery is
located inside the case on the motherboard. Changing the
battery is usually a job for a computer technician. In fact,
a layman might not even be able to find the battery.

If you want to locate the CMOS battery in your computer, be
aware that a static discharge from your hands can damage
components inside the case. After taking proper precautions,
open the case and look on the motherboard for a battery. If
you have a diagram of your motherboard, locate the battery
on the diagram first.

Different motherboards use different types of batteries. The
battery may be shaped like a barrel or a coin. Some
motherboards use a component that resembles a chip which
contains the CMOS and the battery (made by DALLAS or
Benchmarq). Batteries come in different voltages, so make
sure you get an exact replacement.

Sometimes the battery is mounted in a holder. Sometimes it
is soldered to the motherboard. De-soldering and re-soldering
a battery is usually a job for a computer technician. An
inexperienced solderer can cause a lot of damage. If you
want to try to do it yourself, first practice on an obsolete
circuit board. You may change your mind.

If the CMOS battery has failed because it's too old, this
might be an opportunity to upgrade your motherboard. When
upgrading a motherboard, the most important considerations
are to make sure the new motherboard is the correct form
factor for your caseFind Article, and that the new motherboard has the
correct bus connector slots for your expansion boards.

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