What Settings Are in the BIOS?

The BIOS holds settings for the CPU clock speed, memory timings, and more

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The BIOS, or Basic Input Output System, is the controller that allows all of the components that make up a computer system to talk to one another. However, in order for this to happen, there are a number of things that the BIOS needs to know how to do.

This is why the settings within the BIOS are so critical to the operation of the computer system. For about 95% of the computer users out there, they will never need to adjust BIOS settings. However, those who have chosen to build their own computer system or tune it for overclocking will need to know how to modify BIOS settings.

Some of the critical things one will need to know are the clock settings, memory timing, boot order, and drive settings. Fortunately, many of the BIOS settings are automatic and very little needs to be changed.

Note: Many new computers use a system referred to as UEFI which does essentially the same tasks that the BIOS used to. Many people still refer to UEFI as the BIOS.

How to Access the BIOS

The method for accessing the BIOS is dependent upon the manufacturer of the motherboard and the BIOS vendor they have selected. The actual process to get to the BIOS is identical, just the key that is needed to be pressed will vary. It's important to have the user manual for the motherboard or computer system handy whenever changes will be made to the BIOS.

The first step is to look up what key needs to be pressed to enter the BIOS. The BIOS setup utility access key differs between computer systems, motherboard manufacturers, and BIOS manufacturers—some of the common keys include F1, F2, and the Del key. Generally, the motherboard will post this information when the computer first turns on, but it's best to look it up beforehand.

Next, power on the computer system and press the key to enter the BIOS setup utility after the beep for a clean POST is signaled. Try pressing the key a couple times to make sure it gets registered. If the procedure has been done correctly, the BIOS screen should be displayed rather than the typical boot screen.

CPU Clock

The CPU clock speed settings usually are not touched unless you're going to be overclocking the processor. Today's modern processors and motherboard chipsets are able to properly detect the bus and clock speeds for the processors. As a result, this information will generally be buried under a performance or overclocking setting within the BIOS menus.

The clock speed is handled primarily by just the bus speed and multiplier but there will be lots of other entries for voltages that can be adjusted as well. It's advised to not adjust any of these without heavily reading up on the concerns of overclocking.

The CPU speed is comprised of two numbers—a bus speed and a multiplier. The bus speed is the tricky part because vendors may set it either at the natural clock rate or at the enhanced clock rate. The natural front side bus is the more common of the two. The multiplier is then used to determine the final clock speed based on the bus speed of the processor. Set this to the appropriate multiple for the final clock speed of the processor.

For an example, if you have an Intel Core i5-4670k processor that has a CPU speed of 3.4 GHz, the proper settings for the BIOS would be a bus speed of 100 MHz and a multiplier of 34. (100MHz X 34 = 3.4 GHz)

Memory Timings

Another aspect of the BIOS that can be adjusted is the memory timings. It's typically unnecessary for this to be done if the BIOS can detect the settings from the SPD on the memory modules. In fact, if the BIOS has an SPD setting for the memory, this should be used for the highest stability with the computer.

Other than this, the memory bus is the setting you'll likely need to set. This may be listed as the actual MHZ speed rating or it may be a percentage of the bus speed. Check your motherboard manual about the proper methods for setting the timings for memory.

Boot Order

This is the most important adjustable setting in the BIOS. The boot order determines the order in which the computer will boot to each device to look for an operating system or installer. The options typically include the hard drive, optical disk drive, USB, and network.

The standard order at first startup is hard drive, optical drive, and then USB. This means that the computer will look for an OS on the hard drive first, and then look for bootable media on a disc, and then finally search for something on any plugged in USB devices.

Adjusting the boot order is extremely important when you're installing a new operating system or booting to a device other than your hard drive. You have to change the order of the boot devices so that the one you want to boot to is listed before any other bootable device.

For example, if you already have an operating system on the hard drive but you want to boot to a bootable antivirus program instead, you have to first change the boot order so that the disc drive is listed before the HDD. When you restart your computer, the optical drive will be searched first—in this case, the antivirus program will start instead of the hard drive's operating system.

Drive Settings

With the advances made by the SATA interface, there is little that needs to be done by users in terms of drive settings. Generally, drive settings are only adjusted when you're planning to use multiple drives in a RAID array or using it for Intel Smart Response caching with a small solid-state drive.

RAID setups can get quite tricky because you usually need to configure the BIOS to use the RAID mode, and that's the simple part of the setup. You'll then need to create the array of drives using the BIOS from the hard drive controller specific to the motherboard or computer system.

Please consult the instructions for the controller on how to enter the RAID BIOS settings to then configure the drives for proper use.

Problems and Resetting the CMOS

On some rare occasions, the computer might not properly POST or boot. When this occurs, there's usually a series of beeps that are generated by the motherboard to indicate a diagnostic code. Or, an error message might display on the screen with more modern UEFI based systems.

Pay close attention to the number and types of beeps and then refer to the motherboard manual for what the codes mean. Generally, when this occurs, it will be necessary to reset the BIOS by clearing the CMOS that stores the BIOS settings.