Clearing the CMOS

Undoubtedly during your time building a computer, you will encounter a strange BIOS error message, have the Operating System fail to load properly, or even forget the BIOS password. During events like these, you may need to reset the BIOS settings to their default values. There is no need to panic because resetting the BIOS is easily accomplished and this guide will explain how.

Method One - Removing the Battery

There are two ways of resetting the BIOS and the first method involves removing the lithium battery from the motherboard and keeping it out for several minutes. The CR2032 lithium battery is used to store settings such as the time, date, and the BIOS password when the computer is powered off.

I recommend using a flat headed screwdriver to push the metal piece securing the battery to the motherboard to the side and then proceed to lift the battery upwards.

CMOS battery

Once out, set the battery on a clean, dry surface for about five to ten minutes. Once the time has elapsed, re-insert the battery into the motherboard and return the case side cover as well as any connectors to the back of the computer. If done properly, the BIOS should boot up using the default settings when you power the computer on.

Method 2 - Shorting the Jumper

BIOS Jumper Pin

The other method to reset the BIOS involves shorting a specific jumper on the motherboard. This is easily accomplished but be sure to consult your motherboard for the exact name and location of the jumper on the motherboard. The pin with the name CLR_CMOS next to it (shown below) indicates that for this particular motherboard it is the pin to clear the BIOS. Using the metal end of a regular head screwdriver, contact both pins on the CLR_CMOS jumper for approximately 5-10 seconds then remove the screwdriver. Return the case’s side cover and re-attach any connectors to the back of the computer. When the computer is powered on, the BIOS should be reset to the default values.

Replacing the Battery

If you are replacing the battery, be sure to orient the positive and negative sides properly when installing the new one. The positive side, indicated by a “+,” should be facing up if done correctly. Failure to place the battery properly can result in damage to the motherboard.


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