What a BIOS reset does and when you need one

A BIOS reset clears all the settings your computer stored in its firmware — the low-level software that runs before your operating system starts. When you reset the BIOS to factory defaults, you erase any changes made to boot order, CPU speed, RAM timing, security settings, or hardware configuration. Your computer goes back to the way it shipped from the manufacturer.

You reset the BIOS when something you changed is causing problems — a boot failure, random crashes, or a device that stopped working after you adjusted settings. A reset also helps if you inherited a used computer and want to clear out someone else's customizations. It does not erase Windows, your files, or any programs you installed; it only affects the firmware layer underneath.

If your computer boots normally and runs smoothly, you do not need to reset the BIOS. Most people never touch BIOS settings at all. But if you changed something and now the machine will not start, or if you want a clean slate on a secondhand system, a manual reset is the fastest fix.

Key Takeaways

  • A BIOS reset erases firmware settings but leaves Windows, programs, and files untouched on your hard drive.
  • The most reliable method is removing the CMOS battery from the motherboard while the computer is unplugged and powered off for at least 10 minutes.
  • Some newer computers have a CMOS jumper or a reset button inside the case instead of a removable battery.
  • If you cannot open the case or locate the battery, you can often reset the BIOS from within the BIOS menu itself using a "Load Defaults" or "Reset to Factory Settings" option.
  • After a reset, your computer may boot slowly the first time as it redetects hardware, and you will need to re-enter any custom settings you want to keep.

Removing the CMOS battery — the most reliable method

The CMOS battery is a small coin-shaped cell on the motherboard that keeps BIOS settings alive when the computer is off. Removing it for 10 minutes drains all power to the BIOS chip, forcing it back to factory defaults. This method works on almost every desktop computer and many laptops.

Start by shutting down your computer completely and unplugging the power cable from the wall. Wait a few seconds, then press the power button once to discharge any remaining electricity. Open the case — on a desktop, this usually means removing the side panel with two or four screws. On a laptop, you may need to remove the bottom panel, which typically has 4 to 8 screws around the edges.

Locate the CMOS battery on the motherboard. It looks like a large silver coin, usually about the size of a dime or quarter, and sits in a small round socket. Take a photo with your phone before you touch anything, so you remember which way it was facing. Gently pry the battery out using a plastic spoon, a credit card edge, or a plastic pry tool — do not use metal, which can short the board. Set the battery aside and wait at least 10 minutes. Then press it back into the socket the same way it was facing, with the flat side up.

Close the case, plug in the power cable, and turn the computer on. The BIOS is now reset. You may see a message saying "CMOS checksum error" or "CMOS battery low" — this is normal and will disappear after the first successful boot.

Using the CMOS jumper if there is no removable battery

Some motherboards, especially newer ones, have a CMOS jumper instead of a removable battery. This is a small plastic connector that bridges two metal pins on the board, usually labeled CLR_CMOS, PSWD, or CLEAR. Moving the jumper to a different pair of pins for a few seconds resets the BIOS without opening the battery socket.

Shut down and unplug the computer, then open the case as described above. Find the CMOS jumper — it is usually near the battery socket or along the edge of the motherboard. The motherboard manual or a label on the board itself will tell you which pins to use. Carefully pull the plastic connector straight up and move it to the alternate pin pair for 10 seconds, then move it back to the original pins. This clears the BIOS settings.

Close the case, plug in the power, and restart. The BIOS is reset. If you cannot find the jumper or the manual does not describe it clearly, the battery removal method is safer and works just as well.

Resetting the BIOS from the menu if you can still boot

If your computer still boots into Windows or the BIOS menu, you can often reset the BIOS without opening the case. Restart the computer and press the key that enters the BIOS setup — this is usually Delete, F2, F10, or F12, depending on the manufacturer. The correct key often appears on the first screen as the computer starts, or you can check your motherboard manual.

Once inside the BIOS menu, look for an option called "Load Defaults," "Load Factory Defaults," "Reset to Factory Settings," or "Restore Defaults." This option is usually in a menu labeled "Exit," "Advanced," or "Main." Select it and confirm. The BIOS will reset to factory settings and ask you to save and exit. Press the key to save (usually F10) and the computer will restart.

This method is faster than opening the case, but it only works if you can reach the BIOS menu. If the computer will not boot at all, you must use the battery or jumper method instead.

What happens after the reset and what to expect

After a BIOS reset, your computer may take longer to start the first time as the BIOS redetects your hard drive, RAM, and other hardware. You may see messages about the system date being wrong or the BIOS running a configuration check — this is normal and will not happen again. The computer will eventually boot into Windows as usual, and all your files and programs will be there untouched.

Check that your hard drive is recognized and that Windows starts normally. If you had changed the boot order to boot from a USB drive or external device, it will go back to booting from your main hard drive. If you had disabled any hardware in the BIOS, it will be re-enabled. If you had set a BIOS password, it will be cleared.

Once you confirm everything is working, you can re-enter any custom settings you want to keep. If the problem that made you reset the BIOS is gone, you are done. If the problem persists, the issue is likely in Windows or a hardware failure, not the BIOS.

When a BIOS reset does not solve the problem

A BIOS reset fixes problems caused by changed firmware settings — a boot loop after overclocking, a device that disappeared after disabling it, or a computer that will not recognize a new hard drive because the BIOS was set to a wrong mode. It does not fix problems caused by Windows corruption, a failing hard drive, bad RAM, or a virus.

If the computer still will not boot after a BIOS reset, or if it boots but crashes or freezes, the problem is likely hardware or Windows. Try booting from a Windows installation USB to see if Windows itself will start. If it does, Windows may be corrupted and need repair or reinstall. If it does not, a hard drive, RAM, or motherboard may be failing and you may need to test or replace hardware.

If you are unsure whether the reset worked, restart the computer and enter the BIOS menu again to confirm the settings are back to defaults. The BIOS should show the correct date and time (or close to it), and any custom settings you made should be gone.

Frequently Asked Questions

Will resetting the BIOS erase my files or Windows?

No. A BIOS reset only affects the firmware settings on the motherboard. Your hard drive, Windows installation, programs, and files are all stored separately and will not be touched. You will need to log back into Windows and re-enter any custom BIOS settings, but nothing on your hard drive changes.

How long should I wait after removing the CMOS battery?

At least 10 minutes is the standard recommendation to may support all power drains from the BIOS chip. In practice, 30 seconds to a minute is often enough, but waiting longer does no harm and guarantees the reset works. If you are unsure, wait the full 10 minutes.

What if I cannot find the CMOS battery on the motherboard?

Some laptops and compact computers do not have a removable CMOS battery. Check the motherboard manual or look for a CMOS jumper instead. If neither exists, try resetting the BIOS from the menu itself using the "Load Defaults" option. If the computer will not boot, contact the manufacturer for instructions specific to your model.

Do I need to do anything special after the reset?

The computer will boot normally and Windows will start as usual. You may see a message about the system date being incorrect or the BIOS running a configuration check — this is normal and will not repeat. Check that your hard drive and other hardware are recognized, then re-enter any custom BIOS settings you want to keep.

Can I reset the BIOS if I forgot my BIOS password?

Yes. A BIOS reset clears the password along with all other settings. Use the battery removal or jumper method if you cannot boot, or use the "Load Defaults" menu option if you can still reach the BIOS. After the reset, the password will be gone and you can set a new one if you want.