If you are dealing with CMOS errors you are on the correct place. Whenever you switch on your desktop it shows “The firmware has detected that CMOS battery failure has occurred, press enter to continue” then if you click Enter it shows CMOS checksum error, then again if you press Enter it shows CMOS Date and Time not set. Pressing the Enter key again will start the Windows.
Solution to the problem:
The reason for this error might be because the CMOS battery is loosing its charge or it has failed to charge. Solution for this problem is that if you are unable to change your desktop’s date/time settings or every time you find a different date/time or you are receiving the above mentioned errors then it is better to leave your computer switched ON for around 24 Hours as this will help the CMOS battery to regain its charge and work properly.
If the problem still persists, follow these steps:
1. Locate your CMOS battery in the CPU, you can find it on your motherboard and procure all the information about that battery (The part number for this battery for most computers is CR2032) and verify that it is accessible and can easily be removed.
(The battery shown above is a coin cell battery)
2. Try to remove the battery. If your motherboard has the same battery as shown in the picture it is relatively simple to remove the battery. If you are using some other type of battery then it is hard to remove a CMOS battery. However the manufacturers only allow you to add a replacement battery.
3. Get a new battery of same type and insert it at the same place.
4. Once you are done with all of the above steps, Turn ON your desktop and reset the CMOS values to Default and save the settings.
If your computer still shows the same error, it means that you are dealing with some more serious issues. Most likely it would be a bad power supply or some other issues with your motherboard.