How to fix corrupt CMOS in 4 easy steps

by Aleksandar Ognjanovic
Aleksandar Ognjanovic
Aleksandar Ognjanovic
Troubleshooting Expert
Aleksandar's main passion is technology. With a solid writing background, he is determined to bring the bleeding edge to the common user. With a keen eye, he always... read more
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fix corrupt cmos

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Steps to fix corrupted CMOS issues

  1. Reset BIOS to factory values
  2. Flash BIOS
  3. Reset the battery
  4. Replace the battery

A corruption of CMOS is a rather common occurrence. Sadly, it mostly points towards the motherboard failure, but that’s not a rule of thumb. The BIOS/UEFI might be the problem, or the CMOS battery is failing. The estimated longevity is around 3 years, so the latter shouldn’t come as a surprise. And you can try to fix corrupt CMOS with the steps we enlisted below. Make sure to tell us whether they helped you later on.

How to fix corrupt CMOS in a few simple steps

1: Reset BIOS to factory values

The first step you should take when all and any BIOS-related problem appear is to try and restore the default configuration. This is a long-stretch solution if the hardware is broken, but it still might help. Since we need to move gradually towards the battery replacement, let’s give it a shot and, hopefully, the CMOS corruption will be addressed.

Booting into the BIOS/UEFI settings is a rather simple task on previous Windows iterations. However, on Windows 10, due to a Fast boot option, the initial screen will be skipped and you won’t be able to access any of the menus. That’s why we need you to follow the steps we enlisted below and give it a go:

  1. Press Windows key + I to open Settings.
  2. Choose Update & Security.
  3. Select Recovery from the left pane.
  4. Under the Advanced startup, click Restart now.fix corrupt cmos
  5. Choose Troubleshoot.
  6. Select Advanced options.
  7. Choose UEFI Firmware Settings and click Restart.
  8. Reset all settings to default and reboot your PC.

2: Flash BIOS

Now, some errors like the “CMOS checksum” error can appear due to an outdated BIOS. On the other hand, they can appear if you flashed a wrong version of BIOS. That’s why we suggest re-flashing the BIOS, thus updating it to the latest version. Now, even though unaccustomed users see meddling with BIOS as a dangerous task, we wouldn’t say so.

There are only two rules you need to follow when flashing BIOS. Keep the power on throughout the procedure. If your PC suddenly shuts down, chances are you bricked your motherboard. The second rule is to double check the updated version for your exact motherboard model. Flashing a wrong version leads to even worse errors (read: bricking motherboard).

With those in mind, just check your motherboard’s model number and look it up online. If there’s a Flashing tool for your model provided by the OEM, make sure to use it. Some OEMs even offer the direct updating from the BIOS menu, which is even better. But this is hardly a rule, so make sure to check it out before you move to flashing BIOS. You can find out more about the procedure in this article.

3: Reset the battery

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Resetting the CMOS battery is also quite a simple task. It requires you some tools (a small screwdriver basically) in order to remove the side casing from your case. The same goes for the notebooks. Power off your PC and unplug the power source cable. Watch for the  Remove the screws to gain access to the motherboard.

Once there, you should be able to see a small jumper next to the CMOS battery tagged with “Reset CMOS” description. Remove it and keep it off for approximately 20 seconds. Put it back, plug back the powers source, place the casing back, and start your PC.

If you’re not able to locate the jumper, just remove the battery and place it back after 10 minutes. Do it gently to avoid breaking the metal clip which holds it still. We need it to fully discharge before placing it back.

4: Replace the battery

Finally, if the battery died out, you should replace it by following the aforementioned steps. As you can see for yourself, the battery most likely holds the model number CR2032. It’s a standard hand watch lithium coin battery cell. So you shouldn’t have a hard time finding the replacement as it’s widely available.

If the issues persist, the faulty hardware is to blame. Either the motherboard is malfunctioning or the Power Supply Unit is faulty and the replacement is mandatory. For that, you’ll probably need to contact a PC technician so prepare to spend some money if you’re out of warranty period.

With that said, we can conclude this article. If you have any alternative solutions for the corrupted CMOS, make sure to tell us in the comments section below. We’ll be thankful for your effort.


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