If your CMOS battery fails or dies then your computer will have a hard time of remember it's settings and may have a hard time starting up the computer or you may get a CMOS checksum error when the computer is booting up.
Your clock settings may also need to be reset after your computer loses power or drivers stop working or you may lose the ability to use the computer keyboard or computer mouse because the computer is unable to remember the settings.
If you're having those symptoms then I would recommend replacing the CMOS battery as they're not very expensive and they're easy to replace.
When the CMOS battery goes bad in a desktop or laptop computer the computer will be unable to remember its hardware settings when it is powered up.