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BIOS Settings Glossary

ACPI (Advanced Configuration and Power Interface)

ACPI establishes industry-standard interfaces enabling OS-directed configuration, power management, and thermal management of mobile, desktop, and server platforms.

APM (Advanced Power Management)

APM is a set of programs that control the Advanced Power Management system found in most modern laptop computers

BIOS Flash Protection

This function protects the BIOS from being written or corrupted by users authorized and unauthorized. When enabled, data cannot be written to the BIOS chip even with a flash utility. You should enable this function at all times unless you need to update your computer's BIOS version.

Boot-Up Num Lock LED

When this setting is enabled, the Num Lock key will be automatically turned on when the system boots. This enables functionality of the numerical keyboard on full size computer keyboards.

Chassis Intrusion

This option enables or disables recording and warning if a user opens the side panel on a computer. Unless you are concerned with the case being opened, it is safe to turn off.

Chipset-SATA Mode

IDE: Compatibility mode disables AHCI support. AHCI: Supports advanced SATA features such as Native Command Queuing. RAID: Allows multiple drives to be merged into larger volumes for increased performance and/or reliability. Always enables AHCI. Warning: operating system may not boot if this setting is changed after the operating system installation.

Core Multi-Processing

This setting controls whether or not the computer will use more than one CPU core. If this setting is set to “disabled,” then the computer will only use one CPU core. If this setting is set to “enabled,” then the computer will use all of the CPU cores.

Date (MM:DD:YY)

Allows you to set the system clock to the current time. This is important for some operating systems that rely on a properly set BIOS clock.

Extracted Phoenix BIOS modules

STRINGS0.ROM (a.k.a. – STRINGS00.ROM): This BIOS module contains the text strings of all the settings and text instructions that appear in the BIOS. An example of such a string is “Enhanced AHCI:”. This string relates to an item string in TEMPLAT0.ROM which controls this setting. TEMPLAT0.ROM (a.k.a. – TEMPLAT00.ROM): This BIOS module contains the BIOS menu layout, the item strings for BIOS settings, and function calls/functions. This is the module that is modified to add new BIOS menus or reorganize them. The item strings in this file make sting calls to STRINGS0.ROM which allows for easy identification of strings. ROMEXEC0.ROM (a.k.a. – ROMEXEC00.ROM): This file contains many tables such as the BCPNV table which links to several other tables within the file (including the NVRAM Token Table itself – modifying this results in the modification of the factory default settings of the computer).

Frequency Ratio

The frequency ratio setting controls the multiplier of the CPU’s external clock rate. As such, this setting can be used to effectively underclock or overclock the CPU. Example: The CPU in my notebook has an external clock rate of 166.67 MHz. The frequency ratio (aka multiplier)of the CPU is x14. 166.67 * 14 = 2333.33 MHz (2.33 GHz). If the multiplier were set to x15 instead of x14, the new clock speed of the CPU would be 2500MHz (2.50GHz). The value obtained by multiplying the external clock by the frequency ratio is known as the internal clock of the CPU. In the previous example, the internal clock rate was 2.50GHz. Unfortunately, this setting has no real effect in most computers (especially laptops) as Intel usually locks the multipliers of its CPU’s with the PLL. Circumventing this requires a hardware modification.

High Precision Event Timers (HPET)

This provides various ACPI methods to the Operating System, and is recommended to be on unless system instability is noticed.

IOACPI Function

This field enables or disables the APIC (Advanced Programmable Interrupt Controller). It is highly recommended that this option is enabled for Windows Operating Systems. This function will expand available PCI/IRQ resources on your computer.

LAN Option ROM

This option is used to enable or disable a computer's network card from acting as a boot device. You can disable this option to increase BIOS boot time unless you plan to boot your network card as a listener. (Mostly for server environments only).

MPS Table Version

This is used to select the Multi-Processor Specification (MPS) version to be used with the operating system. In most cases, it should be set to [1.4] or [Auto].

PCI Latency Timer

This item controls how long each PCI device can hold the system bus before another PCI device takes over. By setting a higher value, each PCI device is given more time to proccess transactions and as a result will have improved PCI bandwidth. The higher this value is set, the better the PCI performance will be.

Primary Graphics Adapter

This setting determines which graphics card will be booted and utilized first. Standard options for this setting are [OnBoard] [PCI] [PCI-E]. Depending on whether you have a dedicated graphics card or onboard graphics on your motherboard determines this setting.

Quick Booting

Setting this item to [Enabled] allows the system to POST quicker by skipping some system checks such as in depth memory checking.


Enable or disable support for the hard disk's S.M.A.R.T. (Self Monitoring Analysis And Reporting Technology) capability. S.M.A.R.T. is supported by all current hard disks and allows the early prediction and warning of impending hard disk failures.

Trusted Platform Module (TCG/TPM Support)

Enabling this setting allows for encrypted drive keys that are a requirnment for encryption programs to operate such as Microsoft BitLocker.

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