Changing the battery will obviously have the same effect as it failing... a
modern bios should auto detect drives etc and boot with workable default
settings following a loss of backup power. However, worth re-booting and
going to the bios, write down the settings prior to the battery change - just
in case you need to manually restore afterwards!
Also have had a computer with simply a dodgy clock, battery was OK. If you
right click the time and go to the third tab 'internet time' you can resync
your clock to 'windows time' whenever you are on line.
>> Stay informed about: Clock running slow.