Section 8: BIOS/UEFI Settings

The Big Picture: The Control Panel Under Windows

The firmware setup screen is the PC's control panel below the operating system. Menus differ between ASUS, MSI, Dell, HP and others, and names change, but the same handful of settings matter on every PC. This section explains the six that you will meet most often. Golden rule: change one thing at a time, write down the old value, and only change what you understand.

8.1 Boot Order

What it is: The boot order is the list of devices (or boot entries) the firmware tries, from first to last, to find an operating system.

Common devices:

Two ways to choose:

Related settings:

Tip: If you install Windows from a USB stick and it won't boot, check that the stick is shown as a UEFI entry, and that the stick uses a partition scheme (GPT/FAT32) that UEFI can read.

8.2 Storage Configuration (AHCI, RAID)

What it is: The firmware sets how the storage controller behaves. The common modes for SATA drives:

(RAID = Redundant Array of Independent Disks. For example, RAID 1 mirrors two disks; if one dies, the other has all your data.)

The warning: Do not change the mode on a PC where Windows is already installed unless you prepare. Windows loaded the driver for the old mode. After a switch, it often cannot find its own disk and shows a blue screen INACCESSIBLE_BOOT_DEVICE.

What to do if you must switch to AHCI (a well-known method; back up first):

1. In Windows, run an Administrator Command Prompt:
   bcdedit /set {current} safeboot minimal
2. Restart into the firmware setup, switch to AHCI, save.
3. Windows starts in Safe Mode and loads the AHCI driver.
4. In the Administrator Command Prompt: bcdedit /deletevalue {current} safeboot and restart normally.

Check on Windows: Open Device Manager ► IDE ATA/ATAPI controllers. A "Standard SATA AHCI Controller" means AHCI is in use. NVMe SSDs appear under Storage controllers or Disk drives.

8.3 Memory Settings

What it is: Settings that tell the memory controller how fast to run the RAM.

Why RAM often runs slow by default: A DDR4 or DDR5 stick can be sold at "3600 MT/s" or "6000 MT/s", but the default may be the lower standard speed of the JEDEC standard (the industry body that sets memory standards). To get the advertised speed you must turn on a profile.

How to use it: Enter setup, find XMP / EXPO / DOCP (often in an "AI Tweaker", "OC" or "Ai" tab or on the main EZ screen). Choose Profile 1. Save and restart. The PC will do memory training (Section 3.4) and may restart once or twice.

Check in Windows: Task Manager ► Performance ► Memory shows the Speed. Or:

Get-CimInstance Win32_PhysicalMemory | Select-Object Manufacturer, Capacity, Speed, ConfiguredClockSpeed

Speed is the stick's rated speed; ConfiguredClockSpeed is what it actually runs at.

Cautions: The profile is an overclock (running parts beyond their standard spec). It is normally safe and widely done, but a bad combination can cause crashes. If the PC won't start after a change, clear CMOS (Section 7.4).

8.4 Virtualization (VT-x, AMD-V)

What it is: Virtualization lets one PC run virtual machines (VMs): whole "pretend computers" in a window (VirtualBox, VMware, Hyper-V, the Windows Subsystem for Linux 2, Android emulators). The CPU needs special support, and the firmware can turn it on or off.

Why it may be off: Some makers disable it by default for security or old habit.

Symptoms when it is off: VirtualBox/VMware say "VT-x is disabled", the Android emulator won't start, or WSL 2 and Hyper-V refuse to run.

Check in Windows (no setup visit needed):

• Task Manager ► Performance ► CPU: the right side shows Virtualization: Enabled or Disabled.
• Or in PowerShell:

(Get-CimInstance Win32_Processor).VirtualizationFirmwareEnabled

It prints True or False.

Security note: VMs isolate programs from the rest of the PC. Windows itself uses virtualization for some security features (Virtualization-based Security, VBS). Turning virtualization on is safe for normal users.

8.5 TPM

What it is: The TPM (Trusted Platform Module) is a small security chip (or a firmware feature) that stores secrets and checks that the PC's boot has not been tampered with.

Common setup names: "TPM Device", "Security Device Support", "Intel PTT", "AMD fTPM". If Windows 11 setup says "This PC can't run Windows 11" because of TPM, this setting is often just off: turn it on.

How TPM and boot connect: During boot, the firmware measures each stage (hashes it) and gives the result to the TPM. BitLocker releases the disk key only if the measurements match the usual boot. If you change firmware settings (like Secure Boot), the measurements change and BitLocker may ask for the recovery key.

Check in Windows:

• Press Win + R, type tpm.msc. It shows the TPM status and its Specification Version (needs 2.0).
• Or in PowerShell as Administrator: Get-Tpm (look at TpmPresent and TpmReady).

Caution: Clearing the TPM deletes its keys. You could lose access to encrypted drives. Do not clear it unless you have your recovery keys.

8.6 Fan Curves and Thermal Management

What it is: The firmware reads temperature sensors and controls the fans. A fan curve is a graph: it says "at this temperature, spin the fan at this speed".

Fan speed
 100% |                         ╱────
      |                    ╱───
  60% |               ╱──
      |        ╱─────
  30% |───────╱
      +──────────────────────────► CPU temperature
        40     55    70    85  °C

Fan control types:

Typical settings you will see:

Thermal protection. If the CPU gets too hot, it protects itself:

1. It first slows down (thermal throttling: lowers speed to cool).
2. If still too hot, the PC shuts down to avoid damage.

Tips:

• The CPU_FAN header must always have a fan, or the board may refuse to start (or shows a "fan error").
• Do not set a very low curve on a hot CPU for the sake of quiet.
• Dust causes heat. Clean the filters and fans.
• Windows shows temperatures only in some tools. Free third-party tools (for example HWiNFO) read the sensors the firmware exposes. Many makers also offer Windows apps for fan control.

Summary