Now many new computers use a system referred to as UEFI which essentially does the same tasks that the BIOS used to but many people still refer to it as the BIOS.
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. But 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 the BIOS settings of their computer. However, those who have chosen to build their own computer system or tune it for overclocking will need to know how to modify the settings.
Some of the critical things one will need to know are the clock settings, memory timing, boot order and drive settings. Thankfully the computer BIOS has come a long way in the past ten years where many of these settings are automatic and very little needs to be adjusted.
How to Access the BIOS
The method for accessing the BIOS is going to be dependent upon the manufacturer of the motherboard and the BIOS vender 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 is 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. Some of the common keys used to access the BIOS are F1, F2 and the Del key. Generally the motherboard will post this information when the computer first turns on, but it is best to look it up before hand. Next, power on the computer system and press the key to enter the BIOS after the beep for a clean POST is signaled. I will often press the key a couple times to make sure it registered. If the procedure has been done correctly, the BIOS screen should be displayed rather than the typical boot screen.
The CPU clock speed is generally not touch unless you are 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 is 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 have this setting done 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 3.4GHz clock, the proper settings for the BIOS would be a bus speed of 100MHz and a multiplier of 34. (100MHz x 34 = 3.4 GHz)
The next aspect of the BIOS that needs adjusting is the memory timings. Typically it is not necessary 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 a 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 will likely need to set. Verifying that the memory bus is set to the appropriate speed for the memory. This may be listed as the actual MHZ speed rating or it may be a percentage of the bus speed. Check with your motherboard manual about the proper methods for setting the timings for memory.