If the problem persists after turning off the computer, the CMOS Cave battery may be dead or already damaged. Try leaving the computer on for a few days before removing the CMOS battery. Sometimes, leaving the computer on will charge the battery.
In Windows, CMOS stands for Metal Oxide Complementary Semiconductor Manufacturing. This is a sensitive, battery-powered memory that resides on the motherboard of your modern computer. The term also refers to a specific storage technology that helps the Basic Input/Output System (BIOS) program on a new PC store important system data such as date and time settings, boot process, disk information, and other software configurations.
If there is a problem with this memory, a “CMOS Checksum Bad” fatal error will be displayed on your PC before starting Windows. In this guide, we will show you what is causing the error and how to fix it.
What Causes A CMOS Checksum Error On Windows?
“Checksum” describes the value (number or letter) thatOthers are used directly to monitor or verify the integrity of files on a storage device. You will get a Bad CMOS checksum error on your PC when the CMOS memory values are corrupted. This may be due to installing an incorrect or corrupted BIOS update. The CMOS itself is powered by an appropriate dedicated battery, so you may get a CMOS checksum error when the CMOS battery may be low, dead, or old.
Power surges or improper unplugging of the computer can also cause a CMOS checksum error. Despite the many causes, a CMOS checksum failure can be quickly fixed.
Fun fact: CMOS is also referred to as Real Time Clock (RTC), COS-MOS (Complementary Metal Oxide Semiconductor Symmetry), or Non-Volatile Random Access Memory (NVRAM).
How To Fix CMOS Checksum Error
If your Windows PC is experiencing a new Bad CMOS Checksum error at startup, the troubleshooting solutions below should fix the issue.
Perform Automatic Recovery Event
You can also use Startup Repair to fix problems that prevent Windows from starting correctly. Turn on your computer and follow the instructions below.
- When your computer is on, go to Settings > Update & Security > Advanced Startup > Restart Now.
If Windows does not complete startup, turn off your desktop computer and then turn it back on. When the screen turns on, repeatedly press any F8, F11 or any other key until the advanced boot menu appears on the screen.
Another way to load the advanced boot menu is to boot the computer from three consecutive systems. That is, turn on the computer and immediately press and hold the power button until the computer turns off. That’s three times and your computer should load the extended boot menu on the third try.
This tool will definitely diagnose your computer and try to fix system errors that prevent it from booting up properly. Reboot your computer after the process is complete and see if that fixes the CMOS checksum.
Reset BIOS To Factory Settings
Performing a BIOS reset will delete all policies stored in CMOS. From our side, the operation should also remove corrupted data and invalid BIOS values. How you access BIOS and factory reset depends on your motherboard, not to mention the brand of your PC.
See our Windows BIOS reset guide for more information. Be sure to restart your computer and reset the BIOS properly. This will rebuild all checksum values and fix the CMOS error.
Press F1 or F2 on a specific error page to go to the BIOS setup page and select “Load Defaults”Reset, Load Set Defaults, or another commonly used option to restore BIOS default settings.
Some computers require you to press as many different keys (usually Del or F8) to access the Windows BIOS Setup Checker. Check the instructions on each error page to make sure.
After exiting the error page, you can reset the BIOS settings to zero in the Windows advanced boot menu. Shut down your computer and wait 20-30 seconds until it shuts down completely.
- Press the power button and generally hold down the F8 and F11 keys while the PC boots, just before the Windows logo fills the entire screen.
- Select “Troubleshoot”.
The BIOS setup interface varies depending on the make of your PC. However, you should find the Customize BIOS setting in the output section of the current install BIOS sheets.
If you can’t find the In setting, reset your BIOS settings to default values, contact your PC manufacturer, or refer to your device’s instruction manual.
Move the cursor directly to Exit Saving Changes and hold down the Enter key.
The ability to reset your PC’s BIOS to default settings and boot into Windows. To make sure this is a fixed issue, seal your computer and turn your device back on. Try the following troubleshooting step if you are still getting the “Invalid CMOS Checksum” error when starting your computer.
You need to update your BIOS if your PC’s BIOS version does not match the latest version available from the manufacturer’s online store (you can check the Driver Download section of the BIOS). Download theBIOS update tool that matches your PC model, run it with administrator freedom and let the tool update your device’s BIOS automatically.
Before proceeding, please be aware that your current BIOS is a sensitive component associated with your PC motherboard. Installing an invalid update or upgrade, updating the BIOS incorrectly can cause permanent damage to the motherboard. If necessary, carefully follow the instructions of the PC manufacturer to avoid damaging the device.
However, we strongly recommend that you only download BIOS files from your PC manufacturer’s website. Also make sure the BIOS update belongs to your PC, for example. The BIOS file of another installation device on your PC is blocking the motherboard.
Lastly, do not shut down or restart your computer while updating the BIOS. Any interruption (such as a power failure or power surge) during operation can damage the BIOS or motherboard.
Replace This CMOS Battery
As mentioned earlierThat is, your system may not be able to verify the integrity of the new BIOS file if the battery powering the CMOS is dead. Signs of a bad CMOS build include wrong time and data, less competent peripherals, problems connecting to the entire planet, etc.
If we are still getting a CMOS checksum error even after applying these troubleshooting fixes, the CMOS is probably a bad battery. Or maybe it was moved from its place.