This guide explains how to access your system’s firmware settings (UEFI or legacy BIOS) in order to change hardware-level options.
NOTE
UEFI vs Legacy BIOS: UEFI is the modern firmware standard and allows direct access from within Windows. Legacy BIOS is older firmware with no OS-level entry point: the only way in is through keyboard input at boot time (POST).
Check if your System is UEFI or BIOS
Before trying any method, confirm your firmware type.
If you are on Windows
Open PowerShell and run:
bcdedit /enum
Look for the path field:
Output
Firmware type
\Windows\system32\winload.efi
✅ UEFI
\Windows\system32\winload.exe
❌ Legacy BIOS
If you are on Linux
The kernel exposes firmware info directly via the filesystem. Run:
If the system booted in UEFI mode, the kernel mounts the EFI variables filesystem at /sys/firmware/efi. If that directory does not exist, the system booted in legacy BIOS mode.
You can also inspect it manually:
ls /sys/firmware/efi
Result
Firmware type
Directory exists and lists files (e.g. efivars, vars)
✅ UEFI
No such file or directory
❌ Legacy BIOS
UEFI: Enter from Windows
Warning
These methods only work if your system is booted in UEFI mode.
Via CMD command
Open PowerShell as Administrator:
shutdown /r /fw /t 0
Windows passes the /fw flag to the UEFI boot manager, which redirects directly to the firmware setup on next boot. This is the cleanest and most reliable method.
Advanced Startup (GUI)
Navigate to:
Settings → System → Recovery → Advanced startup → Restart now
Or use the shortcut: hold Shift and click Restart.
Once in the recovery environment, follow this path:
The following methods can also work in UEFI firmwares
There is no OS-level method to enter a legacy BIOS. Windows has no communication channel with legacy firmware. The only option is keyboard input during POST.
Key press at POST
Restart the system normally from Windows
As soon as the screen turns on (during POST), repeatedly press the firmware key for your manufacturer:
Manufacturer
Common key(s)
Dell
F2, F12
HP
F10, Esc
Lenovo
F1, F2, Enter then F1
Asus
DEL, F2
Acer
F2, DEL
MSI
DEL
Generic / unknown
DEL, F2, F10
Slow down POST
If the system boots too quickly to catch the key press:
Disable Fast Boot from Windows power settings
Disconnect secondary storage drives to slow down POST enumeration
These are workarounds, not direct entry methods.
⚠️ Last Resort: CMOS Reset
If you cannot access the firmware in any way:
Jumper method: locate the CMOS reset jumper on the motherboard and short it for a few seconds with the system powered off.
Battery method: remove the CMOS coin cell battery (CR2032) for ~30 seconds, then reinsert it.
WARNING
Both methods reset all BIOS/UEFI settings to factory defaults, including boot order, SATA mode, and any custom configuration!
