What is CMOS?

What is CMOS?

CMOS (complementary metal-oxide-semiconductor) battery is needed for your computer to remember the current time and date.

The computer uses this information to track when you last updated the BIOS and other settings.

What is CMOS on The Motherboard Used For?

Because so many hardware components in our computers share the same memory, there is a dangerous downside to them sharing the same space.

If one component fails, it can cause all other components to fail. CMOS, or Complementary Metal Oxide Semiconductor, is the solution to this dilemma.

The CMOS memory chip—which contains date and time information and settings like hard drive order, boot order, and RAM amount—is usually made of solid-state flash memory (like in a digital camera).

When something goes wrong with your computer’s mainboard, you may have found that your computer has stopped working (because it’s trying to access ROM code that doesn’t exist anymore), or you have found no display on your screen when you turn it on.

These symptoms indicate that the troubleshooting process should focus first on your computer’s BIOS—the part of the software that manages what information gets read from where when you turn on or restart your computer.

Lifespan of CMOS

There is no one way to calculate the lifespan of CMOS, and your battery can last anywhere from five to ten years.

However, some factors will affect how long a CMOS battery will work.

  • Battery Type: Some batteries are designed for longer-term use than others. Others have built-in checks and balances to help indicate when they’re getting low.
  • Temperature: This variable cannot be controlled by the user, but it’s important to know that hot temperatures reduce the life of batteries in general while cooler temperatures extend them. Warmer temperatures speed up oxidation (aka corrosion) of chemicals inside a battery.
  • Other Factors: The quality of your computer parts could also play a role in determining how long your battery lasts, which is why it’s important to purchase high-quality components whenever you can!

Benefits of CMOS

While CMOS has some cons, it is still an excellent option for computers.

The pros of CMOS include:

  • Allows the computer to boot faster
  • Stores data even if the computer is switched off.
  • The CMOS battery is not required all the time.
  • Low battery voltage (3 volts)
  • Cheap cost; easily available and easily replaceable

How To Preserve CMOS To Last Longer?

  • Keep your battery away from heat. The battery in CMOS is similar to other batteries. It needs to be kept away from heat that can easily damage the battery.
  • Get a good quality battery for your system. Don’t just get any battery brand or go for something cheap, even if you are on a budget. It would help if you had something that would preserve the CMOS function in your computer.
  • Keep your computer clean and dust-free. When dust accumulates, it affects the system’s performance, which may eventually lead to problems with CMOS. If you notice dust building up inside, use a cloth and wipe off the accumulated dirt as much as possible.

This will help ensure the proper functioning of all computer parts, including CMOS which relies on electricity supplied through circuits that can be easily affected by dust accumulation within the computer housing unit.

What Will Happen If The CMOS is Missing?

If you ever find yourself in a situation where the CMOS battery is missing or has died, don’t worry. Your computer will still work just fine.

However, if the CMOS battery is entirely dead, it will probably cause your computer not to boot at all.


In conclusion, the CMOS (Complementary Metal Oxide Semiconductor) is a vital component of the motherboard.

The information stored in the CMOS helps to make sure that your motherboard functions correctly.

That’s why it’s not advisable to remove the CMOS chip, and therefore, you should maintain it well.

CMOS batteries usually last for about 3-5 years. If your computer is older than five years, then you should consider replacing its battery as soon as possible.

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