Tip & How-To about Computers & Internet

Cmos Battery checksum

So you're PC is more than 3 years old and keeps forgetting things.


1.PC keeps forgetting Time/Date
6.No Operating System

Why does it happen:

There is a 3 Volt lithium battery which keeps such data fresh and as any other battery, it must be replaced when depleted.

1. Get rid of any static electricity in you're body by wearing a grounded wrist strap
2. Disconnect power cable
3. You may damage the main board if battery is replaced incorrectly
4. Do not touch anything else in the computer

How to do fix it:

3. Remove side cover of desktop (some have screws and some just a simple lock and slide)
(it should be the left cover (front facing) you and whole cover in case of a slim case)

4. Locate a shiny rounded metal which looks like a coin and reads CR2032 (may be found in watch repair shops, Radio Shack, etc..)
some PCs use a cylinder type battery a technician may be required to replace itt.

5. Remove battery

6. Replace it with a fresh one keeping in mind orientation of battery (the + sign on top in case of horizontal mounting)
7. Put back cover
8. Connect power cable
9. Boot PC and press "DEL" or "F2" (may be different) depending on vendor to enter setup and update relevant data (Time/Date,on-board raid, etc..)
10. Press F10 to save and exit

good luck.

please rate for more sharings... Thanks

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2 Answers

I have a Dell dimension 9150 which is 2 1/2 years old. Does it have a battery that I need to be concerned about replacing. I remember that used to be a problem with computers but don't know if that is resolved.

Every PC motherboard has a battery. That battery serves two purposes: to feed the configuration memory (also called CMOS) and to feed the real time clock of the computer (the one that show the date and the time).
An indication it is time to change the motherboard battery is receiving one of the following error messages when you turn on your computer: CMOS CHECKSUM FAILURE, CMOS BATTERY STATE LOW, CMOS SYSTEM OPTIONS NOT SET and CMOS TIME AND DATE NOT SET. Another indicator of a low battery is a clock that, after being set, runs well while the computer is on, but shows the wrong time when the computer is turned on the following day (it is late).

Apr 21, 2009 | Dell (2336V) Motherboard

1 Answer


Reseat your ram modules and remove the 2nd hdd
try rebooting
If same thing , then reset the Bios to default ,save and exit
Try again..
If same thing ? assuming you have more then 1 stick of ram,, try booting with 1 stick removed . to eliminate ram modules being bad
then switch ram untill you have verified ram chips are or aren't bad
Hope this helps

Nov 13, 2007 | E-Machines eMachines Desktop PC

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