A computer may sometimes show error messages related to time and date options, or other errors, like "No operating system or new CPU is installed." These are indications that it is time to change the battery of the motherboard, or the CMOS.
Ideally, this battery is due for a replacement once every five years and must be replaced with great care to avoid causing other problems in the PC. Saving BIOS data
prior to the battery change and configuration is strongly recommended.
Identify and Change the CMOS battery
You need to begin by locating the CMOS battery, which is a thin, round, button-like object. It can sometimes be hidden by extension cards or connectors. On older PCs it may have a cylindrical shape.
To access it, turn off your PC and lay your system unit horizontally. Remove the power cable attached to your system unit, and remove the casing. Discharge your system unit from static electricity by touching it with a metallic object.
Once you are sure that the positive pole of the battery is visible, gently remove the battery, taking care not to touch any other part of the motherboard. Go to your local tech parts retailer, and buy a battery of the same or a similar model.
To install it, secure the new battery in the dedicated slot.
Verify BIOS Data and Resetting the Clock
Once the operation completes, it is important to configure the BIOS settings.
Start your PC and enter the BIOS
Modify the date and the time, if needed. Save and quit BIOS.
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