re cmos checksum error in article c uaoq v ulowell ulowell edu mcook cs ulowell edu michael cook writes recently i have been getting a cmos checksum error when i first turn on my computer it doesn t happen everytime i turn it on nor can i predict when it is going to happen i have an ami bios and all of the setting are lost for example the drive types and the password options however the date and time remain correct if anyone knows what can be causing this please let me know most likely reason is that your backup battery is failing this battery maintains the contents of the cmos memory when ac power is turned off and if the battery is flakey then the contents of the cmos will be lost and the checksum will be wrong along with most other of the cmos data try replacing the battery if however your pc doesn t use a battery but a large capacitor to power the cmos you should check to see if you can replace the capacitor with a more normal lithium battery if this isn t possible make sure you leave your pc on for a half hour or hour each day this will keep the capacitor charged i d opt for the battery change though it s also possible but unlikely that a rogue problem or even a virus is corrupting the cmos if your battery seems okay get a virus scanner and check out your system
