Software & Apps Windows 31 31 people found this article helpful What Settings Are in the BIOS? The BIOS holds settings for the CPU clock speed, memory timings, and more By Mark Kyrnin Writer Mark Kyrnin is a former Lifewire writer and computer networking and internet expert who also specializes in computer hardware. our editorial process LinkedIn Mark Kyrnin Updated December 02, 2019 erhui1979 / Getty Images Windows The Ultimate Laptop Buying Guide Tweet Share Email The Basic Input Output System controls the hardware-software communication system that allows all of the components that make up a computer system to talk to one another. You must configure certain BIOS settings to help it initialize properly. BIOS: Everything You Need to Know Some of the critical things one will need to know are the clock settings, memory timing, boot order, and drive settings. Many of the BIOS settings are automatic and very little needs to be changed, and any off-the-shelf computer you purchase will ship with correctly configured 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 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. Press the key several 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. Older computers rely on BIOS exclusively. Newer computers use a graphical boot tool called the Unified Extensible Firmware Interface. UEFI governs the customizations that formerly governed at a BIOS level. Although some people say that UEFI "replaces" BIOS, it's actually the case that UEFI configures BIOS on BIOS-aware systems, removing BIOS access from the end-user configuration. CPU Clock Don't modify the CPU clock speed settings unless you're going overclock the processor. Today's modern processors and motherboard chipsets 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 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 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: 100 MHz x 34 = 3.4 GHz. Memory Timings Another aspect of the BIOS that can be adjusted is the memory timings. It's typically unnecessary to change this setting if the BIOS can detect the settings from the SPD on the memory modules. If the BIOS has an SPD setting for the memory, use it for the highest stability with the computer. Boot Order Boot order 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 the 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 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, drive settings are only adjusted when you're planning to use several 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. 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. A series of beeps generated by the motherboard indicates a diagnostic code, which may require resetting a specific part of the motherboard called the CMOS. 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 error occurs, it will be necessary to reset the BIOS by clearing the CMOS that stores the BIOS settings.