What resetting BIOS does and when you need it

Resetting your BIOS (the firmware that runs before your operating system loads) returns all settings to what the manufacturer set them to. This clears any changes you or someone else made — overclocking settings, boot order changes, disabled hardware, password locks, or corrupted settings that prevent your computer from starting.

Most people reset BIOS when their computer won't start, when they've changed settings and can't remember what they changed, or when they're troubleshooting hardware problems. If your machine is running fine, you don't need to reset it. If you're selling or giving away the computer, resetting BIOS is one step in wiping it clean.

The reset itself takes a few minutes. What takes longer is getting back into BIOS if your computer won't boot — that's where the physical methods come in.

Key Takeaways

  • You can reset BIOS from inside the BIOS menu itself if your computer still starts, which is the simplest route.
  • If your computer won't start, you'll need to open the case and remove the CMOS battery for 10 to 15 minutes, or locate and clear the CMOS jumper on the motherboard.
  • The key to enter BIOS during startup is usually Delete, F2, F10, or F12 depending on your motherboard maker — you'll see a prompt on the first screen.
  • After resetting BIOS, you'll need to set the boot order back to your hard drive or SSD, or your computer will try to boot from USB or CD instead.
  • If you've forgotten a BIOS password, the physical reset methods will clear it, but the software reset from inside BIOS will not.

Resetting BIOS when your computer still starts

If your computer boots normally, the easiest reset is from inside BIOS itself. Restart your computer and watch the first screen — you'll see text saying "Press Delete to enter Setup" or "Press F2 for BIOS" or similar. The key varies by motherboard maker: Dell and HP often use F2, ASUS uses Delete, Lenovo uses F1 or F2, and some boards use F10 or F12. Press that key repeatedly as soon as you see the prompt, before Windows loads.

Once you're in BIOS, look for a menu option called "Reset to Default," "Load Defaults," "Restore Defaults," or "Factory Reset." The exact name and location depend on your motherboard, but it's usually in a main menu or under "Exit." Select it, confirm the action, and the BIOS will return to factory settings. Then select "Save and Exit" or "Exit and Save Changes." Your computer will restart with default BIOS settings.

After the reset, your computer may try to boot from a USB drive or CD instead of your hard drive. If that happens, restart again, enter BIOS, find the "Boot Order" or "Boot Priority" menu, and move your hard drive or SSD to the top of the list. Save and exit again.

Removing the CMOS battery when your computer won't start

If your computer won't start at all, or won't start far enough to let you enter BIOS, you'll need to reset BIOS physically by removing power from the CMOS chip — the small battery on the motherboard that stores BIOS settings. This method works on any desktop computer and most laptops.

First, shut down the computer completely and unplug the power cable from the wall. Wait 30 seconds. Then open the case — on a desktop, this usually means removing the side panel with a screwdriver. On a laptop, you may need to remove the bottom panel, the keyboard, or both. If you're not comfortable opening your laptop, take it to a repair shop; the process is the same but requires more disassembly.

Look for a small coin-cell battery on the motherboard — it's usually silver, round, and about the size of a dime or nickel. It's labeled CR2032 or similar. Gently pry it out with a plastic tool or your fingernail. Leave it out for 10 to 15 minutes. This drains the charge that stores your BIOS settings. Then press it back in, making sure it clicks into place. Close the case, plug in the power cable, and start the computer. BIOS will be reset to defaults.

Using the CMOS jumper on some motherboards

Some motherboards have a jumper — a small plastic connector on three pins — labeled CLR_CMOS, CLEAR CMOS, or PSWD that clears BIOS settings faster than removing the battery. Check your motherboard manual or look for a label near the battery. If you find the jumper, shut down and unplug the computer, then move the jumper from pins 1-2 to pins 2-3 for about 10 seconds, then move it back. This clears BIOS without waiting for the battery to drain.

Not all motherboards have this jumper, so if you don't see one labeled for CMOS clearing, the battery method will work instead. The jumper is just faster if it's available.

What happens after you reset BIOS

After a successful reset, your computer will start with BIOS set to factory defaults. This means the boot order will likely be wrong — BIOS will try to boot from USB, CD, or network before your hard drive. If you see a message like "No bootable device found" or "Boot failure," restart the computer, enter BIOS again, and change the boot order to put your hard drive or SSD first.

You'll also lose any custom settings you had: overclocking adjustments, disabled hardware, custom fan speeds, or security settings. If you had a BIOS password set, it will be cleared by a physical reset but not by a software reset from inside BIOS. Date and time will reset to a default, so you may need to set those again in Windows.

If your computer still won't start after a BIOS reset, the problem is likely hardware failure rather than BIOS corruption. At that point, you'll need to test your RAM, hard drive, and power supply, or take the computer to a repair technician.

Resetting BIOS before selling or giving away your computer

If you're removing personal data before selling or donating your computer, resetting BIOS is one step, but it's not the main one. BIOS reset clears BIOS settings and passwords, but it does not erase your hard drive or SSD. Your files, Windows installation, and personal data will still be there.

To properly wipe the computer, you need to erase the hard drive or reinstall Windows. On Windows, use Settings > System > Storage > Advanced Storage Options > Disk Management to wipe the drive, or use a tool like DBAN (Darik's Boot Nuke) to securely erase it. Only after that should you reset BIOS. The order is: erase the drive, then reset BIOS, then sell or donate the computer.

Frequently Asked Questions

Will resetting BIOS delete my files or Windows?

No. BIOS is separate from your hard drive and Windows installation. Resetting BIOS only clears BIOS settings like boot order and overclocking. Your files and Windows will still be there. If you want to erase your files before selling the computer, you need to wipe the hard drive separately.

What if I can't find the CMOS battery?

The battery is usually near the edge of the motherboard, often close to the RAM slots. If you can't locate it, check your motherboard manual — search online for your motherboard model plus "CMOS battery location." If your computer is a laptop and you're uncomfortable opening it, a repair shop can do this in 15 minutes.

Do I need to reset BIOS if my computer is running fine?

No. Reset BIOS only when you're troubleshooting a problem, you've made changes you want to undo, or you're preparing to sell the computer. A healthy system doesn't need a BIOS reset.

My computer won't start even after I reset BIOS. What now?

If BIOS reset doesn't fix the problem, the issue is likely hardware failure — a bad power supply, failed RAM, or a failing hard drive. Try reseating your RAM (removing and reinserting it firmly) and checking that all power cables are plugged in. If that doesn't work, you'll need to test or replace hardware, or take the computer to a technician.

Can I reset BIOS without opening the case?

Yes, if your computer still starts. Use the software reset from inside the BIOS menu. If your computer won't start, you'll need to open the case to remove the CMOS battery or move the CMOS jumper.