Nonvolatile BIOS memory

[2] It is referred to as non-volatile memory or NVRAM because, after the system loses power, it does retain state by virtue of the CMOS battery.

[3] The CMOS RAM and the real-time clock have been integrated as a part of the southbridge chipset and they may not be standalone chips on modern motherboards.

Other common battery cell types can last significantly longer or shorter periods, such as the smaller CR2016 which will generally last about 40% less time than CR2032.

When replacing the battery cell, the system time and CMOS BIOS settings may revert to default values.

Unwanted BIOS reset may be avoided by replacing the battery cell with the PSU power switch turned on and plugged into an electric wall socket.