What BIOS is and why you might need to open it

BIOS (Basic Input/Output System) is the software that runs before your operating system loads. It controls hardware settings like boot order, fan speed, and memory timing. You open BIOS when you need to change one of these settings — for example, to boot from a USB drive, disable a device that's causing problems, or check your system temperature.

BIOS lives on a chip on your motherboard, not in Windows or macOS. That's why you can't open it like a regular program. Instead, you restart your computer and press a specific key during startup, before the operating system takes over.

Most people never need to open BIOS. But if you're troubleshooting hardware issues, installing a new operating system, or adjusting performance settings, knowing how to get there matters.

Key Takeaways

  • BIOS opens during startup by pressing a specific key — usually Delete, F2, F10, or F12 — before Windows or macOS loads.
  • The correct key depends on your motherboard manufacturer, which you can find by restarting and watching the startup screen or checking your computer's manual.
  • On newer computers with UEFI firmware (the modern version of BIOS), you may need to restart from Windows settings instead of pressing a key during startup.
  • Once inside BIOS, use arrow keys to navigate and read the on-screen instructions for saving changes, since the mouse usually doesn't work.
  • Changing the wrong setting in BIOS can prevent your computer from starting, so take a photo of the original settings before you change anything.

Finding the correct key for your computer

The key you press to open BIOS depends on who made your motherboard. On a desktop, that's usually ASUS, Gigabyte, MSI, or ASRock. On a laptop, it's the manufacturer like Dell, HP, Lenovo, or Apple.

The most common keys are Delete, F2, F10, and F12. Watch your screen during startup — most computers display a message like "Press Delete to enter Setup" or "Press F2 for BIOS" before the Windows logo appears. That message tells you exactly which key to use.

If you miss the message, restart again and watch more carefully. The message usually appears for only a few seconds. If you still can't see it, check your computer's manual or the manufacturer's website. Search for "[your motherboard model] BIOS key" or "[your laptop model] BIOS key" to find the answer.

Opening BIOS on a Windows desktop or laptop

Restart your computer. As soon as it powers on, begin pressing your BIOS key repeatedly — don't wait for the Windows logo. Press it once per second until the BIOS screen appears. If you see the Windows login screen, you waited too long; restart and try again.

On newer laptops and desktops with UEFI firmware, pressing the key during startup may not work. Instead, open Windows Settings, go to System, then Recovery. Click "Restart now" under "Advanced startup." When your computer restarts, select "Troubleshoot," then "Advanced options," then "UEFI Firmware Settings." This takes you directly to BIOS without needing to time a key press.

Once BIOS opens, you'll see a blue or gray screen with text menus. The mouse usually doesn't work here. Use the arrow keys on your keyboard to move between options, Enter to select, and Escape to go back.

Opening BIOS on a Mac

Apple computers use a different system called firmware, not traditional BIOS. On Intel-based Macs (made before 2021), restart your computer and hold Command + R when ready after you hear the startup sound. Keep holding until you see the Apple logo or a spinning globe. This opens Recovery Mode, not firmware settings.

To access actual firmware settings on an Intel Mac, restart and hold Command + Option + P + R instead. You'll see the Apple logo and a progress bar. Let it complete — your Mac will restart automatically.

On Apple Silicon Macs (M1, M2, M3, and newer), firmware settings are hidden deeper. Shut down your Mac completely. Press and hold the power button until you see "Loading startup options." Click Options, then continue. This gives you access to startup security settings, though most firmware adjustments aren't available to users on these models.

Common settings you might change in BIOS

Boot order determines which device your computer checks first when starting up. If you're installing Windows from a USB drive, you need to set USB as the first boot device. Look for a menu called "Boot," "Boot Order," or "Boot Priority." Move USB to the top of the list.

find Boot is a security feature that can prevent some older operating systems or Linux from starting. If you're installing a non-Windows system and it won't boot, look for "find Boot" and set it to "Disabled."

Fan speed and temperature monitoring are in a menu often called "Hardware Monitor" or "System Health." You can check your CPU and GPU temperatures here without opening BIOS every time — most computers also show this in Windows under Device Manager or third-party tools like HWiNFO.

Virtualization settings, XMP/DOCP memory profiles, and CPU voltage adjustments are advanced options that affect performance. Don't change these unless you're following specific instructions for overclocking or troubleshooting, and always photograph the original settings first.

Saving your changes and exiting BIOS

After you change a setting, look for a menu option that says "Save and Exit" or "Exit and Save Changes." Press Enter on that option. BIOS will ask you to confirm — usually by pressing Y for yes. Your computer will restart with the new settings applied.

If you change something and want to undo it without saving, look for "Exit Without Saving" or "Discard Changes." This closes BIOS and restarts your computer with the old settings still in place.

Some BIOS versions have a "Load Defaults" or "Reset to Defaults" option that puts every setting back to factory condition. Use this if you've made multiple changes and something isn't working — it's safer than trying to remember what you changed.

What to do if your computer won't start after changing BIOS

If your computer won't boot after a BIOS change, restart and open BIOS again using the same key. Navigate back to the setting you changed and revert it to the original value. If you can't remember what it was, use "Load Defaults" to reset everything.

If you can't get into BIOS at all — the computer won't respond to the key press — your motherboard has a physical reset. On desktops, open the case and look for a small jumper or battery on the motherboard. Moving the jumper or removing and reinserting the battery for 10 seconds resets BIOS to factory settings. Consult your motherboard manual for the exact location.

On laptops, this is harder to do yourself. Contact the manufacturer's support line or a local repair shop. They can reset BIOS without opening the case.

Frequently Asked Questions

Can I change BIOS settings from Windows without restarting?

No. BIOS runs before Windows loads, so Windows can't access it. You must restart your computer and enter BIOS during startup. Some settings like fan curves or power limits can be changed from Windows using manufacturer software (like ASUS AI Suite or Gigabyte App Center), but these are separate from actual BIOS settings.

Will changing BIOS settings void my warranty?

Changing most BIOS settings like boot order or find Boot won't void your warranty. Overclocking — changing voltage, clock speed, or memory timing — may void it depending on the manufacturer. Check your warranty terms or contact support before overclocking.

Why does my computer keep asking me to press F1 when it starts?

This usually means BIOS detected a hardware change or error. Open BIOS, check that all your drives and devices are recognized correctly, and look for any error messages. If everything looks normal, save and exit. If the message keeps appearing, a device may be failing or disconnected.

Is it safe to change BIOS settings if I don't know what they do?

No. Only change a setting if you know what it does and why you need to change it. If you're following instructions from a guide or support article, follow them exactly. If you're experimenting, take a photo of the original settings first so you can undo your changes.

Can I update BIOS from inside BIOS, or do I need Windows?

Most BIOS updates happen from Windows using manufacturer software or a downloaded file. Some newer computers let you update from BIOS itself — look for an "Update BIOS" or "Q-Flash" option in the main menu. Check your motherboard or laptop manual for the correct method, as it varies by manufacturer.