Question [LAPTOP] CMOS Checksum error after PC is OFF overnight

Apr 6, 2022
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Hello everyone I am new to this forum.

I have an HP-Laptop 17-by1036nr. I recently opened it up to change the battery and a ram stick. I also replaced the cooling paste for the CPU. Since then, I have been having CMOS checksum errors.

CMOS errors only show up when I try to turn on the computer after leaving it off overnight. If I turn off the computer and turn it on again no CMOS Checksum error appears. After every CMOS checksum error I need te reset my BIOS settings including date and time and my action keys setting (I leave everything else in default).

I have flashed a new BIOS (upgraded from version 50 to 74), thinking that it might help, but the problem is exactly the same.

Something else that might be important: Completly shutting down the computer and leaving it overnight, as mentioned, prompts the CMOS error. If I just leave the computer off for a couple of hours no CMOS prompt comes up on startup. Also, after leaving it overnight I am not able to turn on the computer from the battery I need to plug-it in to the wall socket and then turn it on. I get no response form the computer whatsoever unless I do that. This only happens once, afterwards I can normally turn the PC on and off from battery power, and the cylce repeats after leaving the computer off overnight.

Any ideas/thoughts would be appreciated. I have not opened the computer again after replacing the battery.
 

Lutfij

Titan
Moderator
Welcome to the forums, newcomer!

By change, did you replace the stick with another or are you mixing and matching sticks of ram? I think you might need to replace the CMOS battery on your laptop. Prior to doing that, can you remove the battery you used to replace your prior (laptop)battery and run the laptop without the 4/6 cell battery? See if the issue persists during a cold boot.
 
Apr 6, 2022
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Hello, thanks a lot for the quick reply.

I completely replaced the ram stick with a new one.

The power battery on this laptop is integrated so I actually have to open it up to remove the battery. I will try to remove it and report back.
 
Apr 6, 2022
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Welcome to the forums, newcomer!

By change, did you replace the stick with another or are you mixing and matching sticks of ram? I think you might need to replace the CMOS battery on your laptop. Prior to doing that, can you remove the battery you used to replace your prior (laptop)battery and run the laptop without the 4/6 cell battery? See if the issue persists during a cold boot.
Hello,

I have removed the battery and I can confirm that it happened again. The CMOS checksum error occurs every time I start the computer without the battery on.

I could not find a CMOS battery in my machine. Maybe it doesn't have one?
 
Apr 6, 2022
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Yeah, that was what I was thinking.

What do you think may be preventing the CMOS chip from retaining the BIOS data, in this case?
 
Apr 6, 2022
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Yes, once I reset the BIOS settings I can turn the computer on/off and start it from battery power alone. But, if I leave the computer off for a very long time (say, overnight) the CMOS error returns and I can not turn the laptop on unless it is connected to the power cord.
 
Yes, once I reset the BIOS settings I can turn the computer on/off and start it from battery power alone. But, if I leave the computer off for a very long time (say, overnight) the CMOS error returns and I can not turn the laptop on unless it is connected to the power cord.
On battery power after you have reset the bios can you then run the machine for say an hour......no power cord connected.
 
Apr 6, 2022
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Yes. I no longer need the power cord once I have reset the BIOS. I can turn the computer off and back on, on battery power and I will not get the CMOS error.

The error will only return if I turn the computer off for a very long time and then try to turn it back on. As a matter of fact, in this situation, the computer will not turn on, unless I connect the power cord (and I will get the checksum error). Error code is 502.
 
Yes. I no longer need the power cord once I have reset the BIOS. I can turn the computer off and back on, on battery power and I will not get the CMOS error.

The error will only return if I turn the computer off for a very long time and then try to turn it back on. As a matter of fact, in this situation, the computer will not turn on, unless I connect the power cord (and I will get the checksum error). Error code is 502.
I was wondering if you could run the pc on battery power for a hour or two.
 
Apr 6, 2022
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I have an update: I left the power cord connected overnight. Then I disconnected the cord and turned the computer on: no checksum error (the computer turned on as expected).
I will try again tonight.
 
Last edited:
Apr 6, 2022
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Hello again everyone.

Unfortunately the error has returned. I turned off the computer for a few hours after turning it on in the morning and the checksum error has again returned. As I have explained when I get the checksum error I can not turn on the computer unless it is plugged to the wall jack.

Any help, would be greatly appreciated.
 

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