BIOS/UEFI SETTINGS AND TROUBLESHOOTING Lesson Note

BIOS stands for Basic Input/Output System.

It is firmware stored on a computer’s motherboard that performs important tasks when the computer is switched on. It initializes and checks hardware components and helps start the operating system.

BIOS is stored in non-volatile memory, meaning its contents are retained when the computer is turned off.

Examples of hardware checked or initialized by BIOS include:

UEFI stands for Unified Extensible Firmware Interface.

UEFI is a modern firmware interface designed to replace traditional BIOS on most modern computers.

It performs many of the same basic functions as BIOS but provides additional features and supports modern hardware and operating systems more effectively.

Features of UEFI

Traditional firmware interface| Modern firmware interface

Older technology| Newer technology

Usually has a text-based interface| May have a graphical interface

Traditionally works with MBR partitioning| Commonly supports GPT

Has limitations with modern large drives| Better support for modern large drives

Provides basic firmware functions| Provides additional modern features

Common on older computers| Common on newer computers

Note: The term “BIOS” is sometimes used generally to refer to the firmware setup screen even when the computer actually uses UEFI.

BIOS/UEFI performs several important functions.

When the computer is switched on, BIOS/UEFI initializes important hardware components so that they can operate.

BIOS/UEFI performs a Power-On Self-Test (POST) to check whether essential hardware is functioning properly.

The POST process can detect problems involving components such as:

BIOS/UEFI determines which device the computer should attempt to boot from.

Possible boot devices include:

BIOS/UEFI provides settings that allow certain hardware and system features to be configured.

After hardware initialization, BIOS/UEFI transfers control to the appropriate bootloader, which begins loading the operating system.

Modern UEFI systems may provide security features such as Secure Boot, which helps ensure that trusted boot software is used.

POST means Power-On Self-Test.

It is a series of checks performed by the computer’s firmware immediately after the computer is powered on.

The purpose of POST is to determine whether essential hardware is working well enough for the computer to continue starting.

POST may check:

SIGNS OF POST PROBLEMS

A computer may show:

The exact POST behavior depends on the motherboard or computer manufacturer.

The boot sequence is the series of steps a computer follows from being switched on until the operating system starts.

A simplified boot sequence is:

Power On → BIOS/UEFI starts → POST → Hardware Initialization → Boot Device Selection → Bootloader → Operating System

Explanation

BIOS/UEFI setup can usually be accessed during the early stages of starting the computer.

A common method Is to restart or power on the computer and press a designated key repeatedly when prompted.

Common keys include:

The exact key depends on the computer or motherboard manufacturer.

Some modern computers also allow access to UEFI firmware settings through the operating system’s advanced startup options.

Important Precaution

The correct access method should be checked in the computer’s documentation or manufacturer’s instructions rather than assuming that one key works for every computer.

BIOS/UEFI setup contains many settings. The names and arrangement vary between manufacturers.

Common settings include:

The boot order determines the sequence in which the computer checks devices for bootable software.

For example:

Changing the boot order may be necessary when installing or recovering an operating system.

BIOS/UEFI usually contains settings for:

Incorrect firmware date and time can sometimes affect operating-system timekeeping or certain software functions.

Secure Boot is a UEFI security feature designed to help prevent unauthorized or untrusted boot software from running during startup.

It Is commonly associated with modern operating systems.

Some systems provide processor virtualization options, allowing supported software to use hardware-assisted virtualization.

Examples of related settings may include:

The exact name depends on the processor and motherboard.

Some firmware interfaces provide information about:

These options help monitor and manage system cooling.

BIOS/UEFI may display detected storage devices and provide storage-controller settings.

Examples include:

BIOS/UEFI can display information about:

Some systems also provide advanced performance settings.

Firmware may allow administrators to set passwords that restrict access to firmware settings or startup functions.

After making changes, firmware normally provides options such as:

The exact wording depends on the manufacturer.

A user should carefully review changes before saving them.

Troubleshooting is the systematic process of identifying the cause of a computer problem and taking appropriate steps to resolve it.

BIOS/UEFI-related troubleshooting involves identifying problems that occur during firmware initialization, hardware detection or the boot process.

Problem 1:

Computer Cannot Find a Boot Device

Possible Causes

Basic Troubleshooting

Problem 2:

Wrong System Date and Time

Possible Causes

Basic Troubleshooting

Problem 3:

Hardware Not Detected

A component such as RAM or a storage device may not appear in BIOS/UEFI.

Possible Causes

Troubleshooting

Problem 4:

Computer Keeps Restarting During Startup

Possible Causes

Troubleshooting

Problem 5: Computer Does Not Display Anything

Possible Causes

Troubleshooting

Sometimes incorrect firmware settings can prevent a computer from starting properly.

Most BIOS/UEFI systems provide an option to restore default or recommended settings.

This may be labelled:

After restoring defaults, the system may need to be saved and restarted.

Important

Default settings do not necessarily solve every hardware or operating-system problem. If the underlying problem is faulty hardware, damaged software or another issue, additional troubleshooting will be required.

The CMOS is traditionally associated with storing certain firmware configuration information and maintaining system settings using a small amount of power from the motherboard battery.

Modern systems use different types of non-volatile firmware storage and configuration mechanisms, so the traditional term “CMOS settings” is not technically identical to the entire UEFI system.

However, the term is still commonly used when discussing motherboard firmware settings.

A firmware update is a newer version of the software stored on a hardware device that controls its basic operation.

Motherboard manufacturers may release BIOS/UEFI updates to:

Precautions Before Firmware Updates

Note: An incorrect or interrupted firmware update can cause serious startup problems. Firmware updates should be performed carefully and, where appropriate, under qualified supervision.

BIOS/UEFI is important because it:

A technician should observe the following precautions:

SUMMARY

BIOS and UEFI are firmware systems responsible for important functions during computer startup. BIOS is the traditional firmware interface, while UEFI is the modern successor used on most current computers.

BIOS/UEFI performs hardware initialization, POST, boot management and other configuration functions. Common settings include boot order, system date and time, Secure Boot, virtualization and hardware information.

Troubleshooting BIOS/UEFI problems requires identifying symptoms, checking hardware detection, reviewing settings and restoring appropriate defaults when necessary. Care must be taken when changing firmware settings or performing firmware updates.