Do you need a cmos battery for your computer to boot?

Most new computers can automatically determine the correct settings needed for your hardware, and some even store configuration data in a non-volatile Flash chip. These computers effectively do not need a CMOS battery for anything except maintaining the correct time.

Older computers, where you had to specify the parameters for the hard drive in the BiOS, need a CMOS battery. Otherwise, you would have to enter them in every time you booted the computer.