How to Reset CMOS – Recover The Default BIOS Settings

When everything is going according to the norm, most people do not even open their BIOS settings. Overclockers often live within the BIOS, and when their device fails to boot, they often reset the CMOS to recover the default settings and values.

For the regular user, knowing how to do a CMOS reset is not essential, but it can be helpful if their computer fails to boot. There are various ways to go about it, but firstly, it is important to understand what a CMOS is and why resetting it is one of the go-to solutions for boot failures.

CMOS – A Small Memory Circuit

CMOS stands for complementary metal-oxide semiconductor, which is a description of a MOSFET fabrication process. They are often used in integrated circuits, mostly due to their extremely low power usage. In a PC, they are powered by 3V batteries, their lifetime being between 5 to 10 years, depending on the usage and the environment.

The CMOS is used to store the basic input/output system, or BIOS, which holds the necessary data for the computer to recognize the components and communicate with them. It is battery-powered to preserve the BIOS settings when the computer has no power.

Why Reset a CMOS

A CMOS reset can be warranted by many situations. The most common one is a technical difficulty during the boot process. The system does not get to the operating system, thus resetting the BIOS settings to default is recommended. This may clear any and all settings which were at that moment having a negative enough impact for the computer not to boot.

An example would be a gaming motherboard, with overclocked memory and the CPU, but unable to sustain the necessary voltage due to overheating of the voltage regulator module or VRM.

There are a plethora of other issues that can be solved with a very simple hard reset of a CMOS.

How to Reset CMOS – The Simplest Ways

There are a couple of ways to reset a CMOS, the most common and recommended one being the jumper method. Other ways of resetting a CMOS are the battery and a specific CMOS reset button, as well a software reset, through the BIOS.

NOTE: All motherboards have a software way of resetting the CMOS, located in the BIOS settings. It is labeled either Reset BIOS or Reset CMOS or Load Default Values. If entering the BIOS is unavailable, then the following hardware methods should be considered.

How to do a CMOS Reset with a Jumper

This has been a standard method of resetting a CMOS and it works most of the time. The jumper method involves locating the 3-pin connector which is labeled CMOS or CLR C or anything along the lines, which should be in the motherboard manual.

Its location is often very close to the CMOS battery, which is a button battery. It can easily be spotted if not blocked by other components such as a large, 3.5 slot graphics card.

jumper reset bios

The 3-pin connector often has a jumper on it, covering pins 1 and 2, leaving pin 3 visible. The computer should be powered off before the next step. Taking the jumper off and placing it over pins 2 and 3 will clear the CMOS. Waiting between 1 and 5 minutes is recommended before placing the jumper back to its default position.

It is worth noting that some motherboards do not come equipped with a jumper, while still having the CMOS pins. Some motherboards have a 2-pin CMOS reset, but no jumper. Using other conductive metal is recommended in this case. If that is not available, there are other methods.

How to reset CMOS Battery – The Classic Off-On

cmos battery

Battery removal is one of the simplest ways of resetting a device Similarly, by removing a CMOS battery, the BIOS settings will reset. Some batteries are secured, so removing them might take some agility. Before removing the battery, however, the device should be OFF and the power cord should be removed.

Take note of the battery’s positive and negative sides, so that it can be returned properly.

Once more, waiting 1 to 5 minutes is recommended in order for the capacitors to be emptied and the memory completely drained of power. Alternatively, pressing the power button can drain the battery in seconds with the cord out.

Resetting a CMOS with a Dedicated Button

Some motherboards, often more expensive ones, whether gaming motherboards, high-quality ITX motherboards or professional-oriented motherboards, have dedicated clear CMOS buttons. Depending on the board, its revision and maker, the button can either be located on the board itself, either at the top or bottom or outside, with the rest of the I/O.

Pressing this button will clear the CMOS, which is actually the simplest method to do it if such a button is available.

How to Reset CMOS ASUS

ASUS motherboards can be reset by placing the jumper on the necessary jumper pins, either 2 and 3, or just 2 in case the motherboard does not come equipped with the 3-pin connector. If a jumper is not available, any conductive metal will do, like a screwdriver.

Higher quality ROG boards have dedicated buttons and the battery method should work for all boards.

How to Reset CMOS MSI

MSI motherboards can also be reset using the jumper method, whether the actual jumper or any other conductive material. Battery removal will work with MSI boards, just like any other board.

Higher-end boards, like the MEG series, should have a CMOS reset button, usually just below the motherboard chipset.

How to Reset CMOS ASRock

Most newer ASRock motherboards have a 2-pin connector which requires a simple short. Most of them come with the jumper in the box. Battery removal will reset the CMOS, provided that the computer has no other power.

More expensive boards from the Creator, Taichi and AQUA series will have dedicated CMOS reset buttons.

All of these manufacturers have a software way of resetting the CMOS, located in the BIOS settings. This option is, however, often unavailable when boot failures occur.

Conclusion and Summary

The CMOS is a battery-powered memory chip located on motherboards, used to store BIOS settings. Resetting the CMOS is recommended when a personal computer runs into boot issues or other issues with corrupted BIOS values.

Resetting can be done in four different ways, using the reset option in the BIOS settings, using a jumper to reset it, taking out the battery while the computer has no power and if available, using the CMOS clear or reset button. This will reset the BIOS to default, factory values. This should help with troubleshooting, or it can be a solution on its own.

About The Author

Milan Zagorac

Milan has always been interested in writing and technology, but managed to pick up a love for music, literature and sports along the way. Essentially a jack of all trades, his interest in all things tech as well as love for the written word, keeps him well occupied.

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