Troubleshoot CMOS Errors on PC Start Up
To troubleshoot your PC when it is experiencing persistent start-up errors, take a look at the words that scroll across the screen on start up to see if the errors say anything about CMOS. If so, it may be a dead motherboard battery.
Yes, your computer has an internal battery. That battery keeps track of the time while the computer is turned off. On ancient computers, it also maintained something called the CMOS (say “see moss”). So a telltale sign of a CMOS error, and therefore a dead PC battery, was that the word CMOS appeared in the error message. For example:
98304K 162-System Options Not Set 163-Time & Date Not Set The following configuration options were automatically updated: Disk 1: 2428 Mbytes If you are running Unix, you need to configure your system using the COMPAQ User Diagnostics diskette. Total memory installed: 98304 Kbytes Diskette Drives CMOS checksum invalid, default values loaded F1: Save Changes Compaq Deskpro 4000
To the trained eye, the information in this start-up text error message says a lot. Don’t concern yourself with those details; just note the line that says CMOS checksum invalid. That’s the clue that the PC needs a new battery.