Did you know there’s a battery on the PC’s motherboard? Here is what the CMOS motherboard battery does and why you require it. If you are utilizing your older desktop PC or a laptop, the PC’s motherboard has an integrated battery.
But unlike the standard laptop battery, your motherboard’s battery does not power the PC while you are utilizing it. Quite the opposite, actually, the battery (recognized as CMOS) is small and only active when you are not utilizing the PC. So, why’s there the battery on your motherboard, and what is it for? How long does the CMOS battery actually last? Let’s find out.
What Is The CMOS Battery?
CMOS is short for complementary metal-oxide-semiconductor. In the early days of personal PCs, CMOS RAM (a volatile memory type) saved BIOS settings. CMOS RAM needs a battery; the settings would otherwise be lost when your computer was turned off.
Modern PCs do not make use of CMOS RAM anymore. They save the BIOS settings in the non-volatile memory, which denotes that the settings do not require continuous power to be stored. Meanwhile, the modern UEFI motherboards save settings on the flash memory or on your PC’s hard drive. No battery is required on such systems, but you will frequently find it anyway.
What Is UEFI?
The UEFI stands for Unified Extensible Firmware Interface. This specification was presented for supplanting BIOS. The industry-wide standard established by the chip companies AMD and Intel, along with PC manufacturers and Microsoft, UEFI improves on the BIOS.
Because of its roots back in the 1980s IBM-compatibles era of the personal PCs, BIOS has a few limitations. UEFI actually overcomes such, appending, for instance, support for the drives of 2.2TB or larger, thirty-two-bit and sixty-four-bit modes, and Secure Boot.
This final feature is a way of securing your computer. The Secure Boot makes sure that the malware doesn’t exploit a PC’s boot process. It does so by simply checking that any code executed at startup has a valid digital signature. Other UEFI features comprise overclocking, boot selection, and configuring different motherboard-specific settings.
What Is BIOS?
Instead of UEFI, the older PCs make use of BIOS (Basic Input/Output System) saved in the chip on the PC’s motherboard. When the PC starts up, the BIOS boots up, performs a POST (power-on self-test), and initializes your PC’s hardware.
The BIOS then simply passes the control over to the boot loader, frequently on the hard drive. (A boot loader can also start from the optical disc or USB device.) The boot loader then loads the OS, mac OS, Linux, Windows, or whatever.
The BIOS is actually responsible for low-level system jobs. You can enter the PC’s BIOS settings screen by simply hitting a key during boot. The BIOS settings screen permits you to configure the low-level settings for the PC’s hardware.
Such vary across motherboard companies, but a few choices are universal. An example is changing your PC’s boot order, the order in which your PC actually loads OSs from the connected storage.
Why Does The Motherboard Require A Battery?
So, if a lot of PCs save BIOS settings in non-volatile memory, why do motherboards still have batteries? Simple: Motherboards still comprise RTC (Real Time Clock). Power the PC on or off; the battery still runs all the time. The RTC is essentially a quartz watch, like the old wristwatch. When your PC is off, the battery gives power to the real-time clock for running. That’s how the PC always knows the right time when you turn it on.
When Is It Time To Actually Replace The Motherboard Battery?
As we all know, batteries do not really last forever. In the end, the CMOS battery will stop functioning; they usually last up to ten years. The regular use of the PC denotes the CMOS battery can last longer.
Conversely, the battery in a PC that’s frequently powered off will expire sooner; it is utilizing the battery more, after all. If your battery fails on the older PC that saves the BIOS settings in CMOS, you will see error messages such as:
CMOS Checksum Error
CMOS Read Error
ACPI BIOS Error
CMOS Battery Failure
New CPU Installed
This final one is particularly puzzling at first, but the explanation is easy. Without the battery powering your BIOS, your motherboard cannot remember that your CPU was installed already. As such, it thinks it is new each time you start the PC.
On the newer PC that saves the BIOS settings in the non-volatile memory, your PC might start normally, but your PC may stop keeping a record of the time when it is turned off. It can cause connection problems and issues downloading updates, so it’s worth resolving.
How Can You Replace Your Motherboard’s CMOS Battery?
To resolve such issues, you will have to replace your CMOS battery, a little silver disc situated on your motherboard. Frequently a CR2032 battery, it is also utilized in watches, calculators, and other electronic devices. Before moving on, you ought to turn off the PC, take out the power cord, and, if utilizing the laptop, disconnect its battery. Take care to follow the standard computer maintenance steps when opening the computer, and be cautious of static electricity.
Note that the battery might be soldered onto your motherboard in a few PCs. It’ll need a full replacement of your motherboard or the repair done by the manufacturer.
Pull Your CMOS Battery For Troubleshooting Computer Problems:
Taking out and re-inserting the CMOS battery (recognized as pulling) might also be utilized as the troubleshooting step on older PCs. For instance, if a PC has the BIOS password, taking out and replacing your CMOS battery will wipe the password. Note that your other BIOS settings will also be cleared, however.
(If your PC saves the password in the non-volatile memory, it will not help. You may otherwise locate a way for resetting your password utilizing the jumper on your motherboard.) You can also reset your BIOS settings from within your BIOS, assuming your PC is starting properly. Search for a choice named Reset to Defaults or Clear CMOS.
That’s Why The Motherboard Has A Battery:
So, now you know why there’s a battery on the motherboard:
- On older PCs, the CMOS battery contains the BIOS settings
- For more recent devices, a CMOS battery powers your computer’s clock
Replacing the CR2032 battery on the motherboard is simple, although, in a few situations, they are fixed to your motherboard. Luckily, CR2032 batteries are simple to find, so replacement should not be a problem.