Folks how often do you face the problem where the PC is showing a wrong time and date? Repeatedly even after you change it doesnot work so be rest assured that it is the problem with the CMOS battery on your Motherboard. Now whan and how to change that battery? Well whenever your PC boots up giving the message like -CMOS Battery Failure, it is the right time to change the battery. You don't have to worry much, because you can change the battery yourself.