Symptoms
- Keyboard/mouse doesn't respond on the BIOS or boot menu screen
- Devices work fine once the operating system fully loads
- Wireless keyboard/mouse specifically doesn't work at boot
- Issue happens only when trying to enter BIOS or boot options
Likely causes
- CommonUSB port used doesn't have legacy/BIOS support enabledSome USB ports, especially USB-C or certain rear ports, aren't initialized that early in boot unless a BIOS setting allows it.
- CommonWireless keyboard/mouse relies on OS-level drivers not yet loaded at bootBluetooth and some wireless connections often aren't available until the operating system's drivers load.
- Possible'Legacy USB Support' disabled in BIOS/UEFI settingsThis setting specifically controls whether USB devices function before the OS loads.
- Less commonFaulty USB port on the motherboardA specific port might not function early in boot even if it works normally once Windows starts.
What to do
- Try a different USB port, especially one directly on the back of a desktop connected straight to the motherboard.
- If using a wireless keyboard/mouse, try a wired one temporarily to enter BIOS, since wireless devices are less reliable at that stage.
- Enter BIOS (usually by pressing a key like F2, F10, F12, or Del during startup, check your manufacturer) and look for a 'Legacy USB Support' or 'USB Configuration' setting, enabling it if disabled.
- Update the motherboard's BIOS/UEFI firmware from the manufacturer's website if a newer version is available.
- Check if the keyboard/mouse manufacturer has a wired mode or dongle, which sometimes work better at boot than a Bluetooth wireless connection.
- Test the mouse/keyboard on another computer's BIOS screen to confirm the device itself supports early boot use.
- If nothing works, keep a simple wired keyboard/mouse on hand specifically for BIOS access.
Tools and parts
- Wired keyboard or mouse (as backup)
Basic wired keyboardSearch: “simple USB wired keyboard”
When to call a pro
If a wired keyboard also fails to respond in BIOS after enabling legacy USB support, a technician should check the motherboard's USB header or CMOS battery.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.