Came home computer was on black screen and now it won't reboot. When I try to reboot, I get a "cmos checksum error ". Keyboard also isn't working. What could be the problem?

Check CMOS and Memory Modules:::If the error message is "UNEXPECTED_KERNEL_MODE_TRAP," then it indicates you have problem with the memory of your computer. You need to check whether the SIMMs (Single Inline Memory Modules) are compatible and have the same speed. Secondly, also check whether you have set the CMOS (Complementary Metal Oxide Semiconductor) to the right amount of RAM. If these solutions do not work, you might have to replace memory in your computer....try to use system utility tool like Reginout.. Hope the problem is resolved.

This error is not the same as a CMOS Checksum Error, which refers to corrupted values of the CMOS settings, the ones you set through the BIOS setup program. This error means the contents of the BIOS code itself are damaged.

During the boot process you will see on the screen to press delete to enter setup
Press and hold delete during the boot up process to enter BIOS you can load failsafe defaults or load optimized defaults ,press escape then press f10 to save to cmos to restart
click start control panel date and time you can make your adjustments to the date and time from there also right click on the date and time on the bottom toolbar (bottom of screen) you should see Adjust date and time tab
hope this helps you

Solutions to CMOS Checksum Bad Error

The CMOS Checksum Bad Error can be fixed easily by following the listed steps carefully.

CMOS Battery may not be functioning properly

If you suspect that your CMOS battery is not functioning properly, you can easily change it. Before changing your battery, reboot your computer to make sure that the error still exists. If it does, go into your CMOS and write down all of the settings. If all the settings are lost, you can usually retrieve them from your computer manufacturer. Now locate the battery and remove it, you might need to consult your computer's manual or technical support to remove your battery (the battery a flat, shiny silver colored and coin-shaped). Take down the CMOS battery's information such as volt, size, etc. Once you have your new battery, you can replace it and reenter your CMOS settings. If your battery was the cause of the CMOS Checksum Bad Error, you should have solved the problem.

Your BIOS may have been updated

If your BIOS have been updated recently, your CMOS settings may have reset. Make sure that the values entered in the BIOS are correct or simply reset them to the default settings. If you believe that a virus has updated your BIOS settings, run a virus scan and make sure that the BIOS settings are back to the default.

The Computer may not have been shut down properly

Sometimes when running MS Windows, if you shut down your computer without first properly shutting down your operating system, it will corrupt the CMOS settings causing the CMOS Checksum Bad Error. You can easily avoid this error by making sure that you completely shut down your computer properly before turning off the main power. Usually this entails going into the Start Menu, clicking on Turn Off Computer/ Shut Down. If improper shutdown was the cause of the error, you may have solved the issue.



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CMOS checksum errors
Explanation: A checksum is computed as an error-detecting code, to protect the BIOS settings stored in the CMOS memory. Each time the system is booted this number is recomputed and checked against the stored value. If they do not match, an error message is generated to tell you that the CMOS memory contents may have been corrupted and therefore some settings may be wrong. BIOSes react in different ways to encountering this sort of error. Some will warn the user and then continue on with whatever settings were in the CMOS. Others will assume that the settings that were in the CMOS were corrupted and will load default values stored in the BIOS chip "for safety reasons". The error message will indicate which your system is doing.
Diagnosis: The most common cause of checksum errors in CMOS is a battery that is losing power. Viruses can also affect CMOS settings, and motherboard problems can also affect the stored values.
Recommendation: Follow the instructions in this section to address the CMOS corruption. You should make sure that all of the BIOS settings in the system are correct, by rebooting the system, going into BIOS setup and double-checking all the values (hopefully against a recent BIOS settings backup).

You need to completely shut down your system. Power off. Unplug the power cord for 3 or 4 minutes. Plug the cord back in and try again but I would do so the first time without the new mouse and keyboard. Checksum errors are ram memory errors most of the time. the ACHI Bios error is bad new also. I think one or more of the new devices is bad. They could have a dead short in them that is causing severe problems with your PC that if it continues could cause some real damage.

ok, after reading i noticed that the computer cant find anything, not even the keyboard which is why f1 doesnt do anything, none of the controllers are registering, im beginng to think the mainboard in the laptop is dead. the main thing is the cmos error, usually when that happens the battery for the cmos has died, but even if we put a new battery in there is the possibility the keyboard wont work......so the first thing is to replace the battery, not the laptop battery but a small watch battery inside the laptop, are you able to do this yourself? if not can you take it to someone who can? The CMOS checksum error is the first problem thats on my mind.

You can try flashing/updating the BIOS if nothing works.

Ports are usually labelled - look carefully.
Try manufacturers manual.
Could be that keyboard is the larger 5 pin DIN socket (old IBM AT keyboard).

Press DEL to enter setup and set Reset to Defaults in Exit menu. If you have USB keyboard, make sure you enable Legacy USB and USB keyboard settings, save and exit and reboot.

cmos checksum errors are caused by a bad battery.
If that dont work then the board is bad from the factory.