The BIOS, short for Basic Input / Output System, is an important chip on your motherboard. It stores all the essential configurations of of your system’s components in a non-volatile ROM (read only memory) chip on the motherboard. It tests your system’s components during the boot process, called POST (Power-On Self Test), to ensure that all the parts necessary for a successful boot are present and functioning.
While all motherboards have a BIOS, a fancy user interface was only introduced with UEFI (Unified Extensible Firmware Interface). Here, you can navigate through all the settings with your mouse, and features, dependent on the brand of your motherboard, are presented to you with graphics to help explain their purpose and effect.
There are many settings within the BIOS to tweak your memory timings and performance, to fine-tune settings of your CPU settings, and tweak your motherboard features. You should be sure about what you are fiddling with before hitting the “Save and Reset System” button, usually found on the last page of the BIOS, as some settings, can cause unexpected behavior or even catastrophic failures. If your system refuses to boot after you have changed settings, you will need to reset the BIOS to its default values and start over. Let’s take a look at how to do this.
The easiest option to reset a BIOS is to do it within its interface. Usually located on the last page of the BIOS, you will find the option to load the default settings. This can of course only work, if you still can access the BIOS. Should you have made changes so that the system won’t post anymore, you will need to use a manual method by accessing batteries, jumpers, or buttons on your motherboard.
The first thing you should do is check your motherboard's manual for instructions on how to reset the BIOS. It will tell you which manual method is supported by your motherboard, and it may be as simple as pressing a button on the board or I/O panel while your system is powered off.
Not sure what motherboard model you have? Look around on the board itself to find the model information (Or check out our article about finding out which motherboard you have), and then do a quick Internet search to find the manual for it on the manufacturer's website. Keep in mind that this information may be hidden under your graphics or other expansion cards installed in your system. If you are still not sure, you can search your board for visual clues based on the methods described below.
Your system must be turned off to reset the BIOS. Ideally, you should also turn off the power by flipping the switch on the unit itself and/or unplugging the power cord. All LEDs on the board should be off. It may help to press and hold the case's power button several times for a few seconds to drain any remaining power from the board.
If your motherboard has a jumper to reset the BIOS, you can find it placed over a set of 3 pins, or simply 2 bare pins on the board.
If there are 3 pins, two of which are connected by a jumper, you will need to move that jumper to bridge the previously open pin and the middle pin. Wait a few seconds, then move the jumper back to its original position.
If you only see two bare pins to reset the BIOS, you will need to bridge them either with a jumper or very carefully with something like a screwdriver head. Be very careful that you only short the two pins and do not touch anything else on the board. If the pins are in a hard-to-reach place, and the CMOS Battery is easier to access, you should use that method instead.
To permanently store settings for the BIOS to read, a small volatile memory is present on the motherboard called CMOS (Complementary Metal-Oxide-Semiconductor). As this memory needs a power source to store the information, even when your system is unplugged, every motherboard is equipped with a coin cell type battery. To reset the settings stored in the memory, you can therefore simply remove the battery and install it again. Your BIOS will use the default settings afterwards. This is a far easier method than the jumper, but, if you've got a fancy motherboard, there's an easier method still.
Some motherboards have a reset button either on the I/O panel or on the board itself. Resetting the BIOS can here be done with a simple push of a button.
