How To Clear The Cmos On A Motherboard

Resetting your motherboard is not something that you would want to do often. It should always come as a result of troubleshooting a serious problem related to your hardware.

In the following text we will talk in depth about how to reset motherboard using simple methods.

Essentially, to reset your motherboard, you need to reset the BIOS. The BIOS is the most basic operating system that a computer uses to initialize the computer hardware when you switch it on.

A motherboard reset is often required when either a hardware component (like a graphics card) malfunctions or when a newly added hardware fails to detect or work.

For instance, if you recently overclocked your CPU and you have then started to notice issues, it is best to reset the BIOS.

It may also be required when your motherboard seems to be malfunctioning. For instance, often times when a motherboard malfunctions, it does not go past the POST – you will see it turn on flash some lights and then turn off. This may continue on a loop.

But besides that, their can be a myriad of issues that can warrant a motherboard reset including issues related to BIOS flash.

Few Important Terms to Understand

What is BIOS?

BIOS stands for Basic Input/Output. This is the most low-level operating system that comes pre-installed with all motherboards.

You can think of this as the first program that talks to the hardware on your PC. Hence in the BIOS settings, you will often find myriad of details and settings related to your hardware that you can check and modify – such as overclocking your CPU etc.

Also Read: How to Check if CPU is Overclocked?

What is POST?

POST stands for Power On Self Test. This is basically a test that the BIOS performs to check if all the hardware is in order.

If any critical hardware fails on startup, you may see the issue prompted on the screen or in the form of beep codes or LED flashes. These would indicate where the issue lies. For instance a 5 beep code sound would indicate an issue with the CPU etc.

POST can be a great way to identify what the issue with your motherboard/PC is.

Also Read:

Will Motherboard Post Without CPU?
How to Test Motherboard Without CPU?

What is CMOS?

CMOS stands for Complementary Metal-Oxide-Semiconductor. This is the chip where the BIOS settings are installed.

If you have made any changes to BIOS, or if any changes have been inadvertently made to the BIOS settings, then clearing CMOS would reset the motherboard.

Also Read: How To Connect Power Button to Motherboard?

How to Reset Motherboard? – Resetting BIOS

Resetting the BIOS can be done in a variety of ways.

There are essentially 3 ways to reset your motherboard:

Resetting the BIOS Internally
Resetting CMOS by Removing the CMOS Battery
Resetting CMOS Through the Clear CMOS Jumpers

Method 1: Resetting from the BIOS Menu

This is most non-invasive and the easiest method to try out before going into the more technical methods listed below.

Your computer needs to be restarted for this. Find the specific key you need to press to access the BIOS on your computer. Some popular ones are F2 and F12.

As the computer restarts, repeatedly press on the specific key you identified before you see the first logo. You will have a short window of time to do this.

When successful, you will enter the BIOS of your PC.

The setting you need to find is called "Setup Defaults" or something similar like "Load Default Configuration" etc.

Save the settings in your BIOS and restart.

If your specific issues resolve after this, then no go any further. If they don't then you have to clear the CMOS using the methods below.

Method 2: Resetting CMOS by Removing the CMOS Battery

Recall from earlier that CMOS is a chip that stores the user defined settings in the BIOS. So if you have made any changes to your hardware, this is where they get stored.

Sometimes CMOS settings can also get corrupted and that may warrant a reset. One popular method is to disconnect the CMOS battery from the motherboard.

The CMOS battery enables the motherboard to keep the settings such as the time, date and your user defined BIOS settings intact even when the computer turns off.

Disconnecting it will clear all CMOS settings.

Step 1: Disconnect PC Power Supply

Turn your PC off and remove it from the cable from the wall socket.

Step 2: Locate the CMOS Battery On Your Motherboard

This is fairly hard to miss. It's a small coin cell that you need to disconnect.

Take note of its negative "-" and the positive "+" terminal or the orientation of how the battery is placed. You will need to know this when putting the battery back.

Step 3: Unlock the Latch/Locking Mechanism

Most CMOS Battery holders have a latch or a locking mechanism to keep them in place.

Try to open it using a precision screwdriver without applying a lot of force. As you push on the latch, you may see the battery lift up.

Step 4: Carefully Remove the Battery

Carefully remove the battery from its holder.

Cmos battery remove

CMOS battery removed

Step 5: Reconnect the Battery After 1-5 Minutes

Do not immediately put the battery back in.

Wait for a couple of minutes and give the CMOS the time to drain all of its residual power.

Carefully reconnect the battery. You will hear the latch make a clicking sound once it is in place.

Make sure that you take care of the negative "-" and the positive "+" terminal of the battery.

Import Points to Note Here

Time and Date Will be Reset:

Removing the CMOS will reset the system's clock. A warning will be presented to you that the time is not set.

If the time and date did not reset to default, then that indicates that your CMOS clearing attempt did NOT succeed.

Replacing the CMOS Battery May Be Warranted

It is also worthwhile to replace the CMOS battery if the issues persist.

There are many issues that indicate that the CMOS battery is low. For instance, if your PC turns off without any notice or without any obvious underlying issues with the rest of your hardware, then replacing the CMOS battery could help.

Also Read: How to Tell if RAM Will Work With Your Motherboard?

Method 3: Resetting CMOS Through the Clear CMOS Jumpers

Another fairly simple way to reset your motherboard is to use the the Clear CMOS Jumpers.

Jumpers are basically very short terminals on the motherboard that serve a specific electrical purpose. For instance, there are jumpers for powering on the PC, jumpers for motherboard speakers and jumpers for powering the front CPU Case LEDs.

In this case, we are interested in the Clear CMOS Jumper

Step 1: Disconnect PC Power Supply

Turn your PC off and remove it from the cable from the wall socket.

Step 2: Locate the Clear CMOS Jumper

You can either refer to your motherboard to find the location or look for the labels on the motherboard itself.

The label on my motherboard read "CLR_CMOS" indicating the jumpers intending for clearing the CMOS.

Do note that different motherboard may have different types of clear CMOS jumpers. Some motherboards have a clear CMOS jumpers with 3 pins, hence you may have to refer to your motherboards manual.

clear cmos labels — CLEAR CMOS Jumper Labels

Often time, the labels on the motherboard clearly tell you how the jumper works. For instance in my case it tells me:

Open: Normal – when the jumper is as it is (open) it works normally
Short: Clear CMOS –when the jumper is shorted CMOS will clear.

Short meaning when circuit is closed i.e when an electrical connection is established between the two terminals.

Step 3: Shorting the Jumper

As mentioned, my Clear CMOS Jumpers indicate that shorting them would clear the CMOS.

Clear CMOS screw driver

Just grab a precision screw driver, and place it so that it contacts both terminals at the same time. Hold it for a minute or two.

Ideally you should use jumper blocks, but a screw driver works just fine in case if you do not have a spare jumper block.

This should clear the CMOS and thus reset your motherboard to defaults.

You will know if your motherboard has been reset to default if the Time and Date of your system when you turn it on have also reset to default.

(BONUS) Method 4: Resetting Using the Dedicated Motherboard Reset Button

Some motherboard have a dedicated push button for clearing CMOS. Check if your motherboard does too as that would make things a lot easier.

Also Read: Can You Use NVIDIA Graphics Card with AMD Processor?

Caution

For all the methods that involve working directly on the motherboard, you will need to ensure that you have safely grounded yourself to release all static electricity.

Any static charge on your body can cause damage to the system.

FAQ

Does Resetting Motherboard Erase DATA?

No, a CMOS reset or resetting BIOS to default will NOT erase your data on the hard drives.

It will NOT delete any of your files or remove your operating system.

Is it Safe to Reset the BIOS to Default?

Yes, resetting the BIOS to defaults is perhaps the safest thing that you can do.

If you ever tampered with the hardware default settings such as the voltage, clock speed etc resetting BIOS is not only safe, but the recommended course of action.

Also Read: How to Use Motherboard HDMI with Graphics Card?

Final Words

Here we talked comprehensively about different ways on how to reset motherboard. Resetting a motherboard returns it to the default settings as configured by the manufacturer. Resetting the motherboard essentially resets the BIOS.

This will NOT affect any data in the hard drives. Your data will remain in tact. Resetting BIOS is not the same as reformatting the computer's operating system. The former resets the hardware, while the later resets the software (OS).

When in doubt regarding the performance of your hardware or if you are experiencing issues due to a recent change you made to the hardware default settings, then a motherboard reset is recommended.