If you happen to’re utilizing an older desktop pc or a laptop computer, your pc’s motherboard comprises an built-in battery. However in contrast to a regular laptop computer battery, the motherboard’s battery does not energy your pc whilst you’re utilizing it.
Fairly the other, actually—the battery (often called “CMOS”) is tiny and solely lively whenever you’re not utilizing your pc.
So, why is there a battery on the motherboard and what’s it for? How lengthy does a CMOS battery final? Let’s discover out.
What Is a CMOS Battery?
CMOS stands for complementary metal-oxide-semiconductor. Within the early days of private computer systems, CMOS RAM (a unstable reminiscence sort) saved BIOS settings.
CMOS RAM requires a battery; the settings would in any other case be misplaced when the PC was switched off.
Fashionable computer systems do not use CMOS RAM anymore. They retailer the BIOS settings in non-volatile reminiscence, which signifies that the settings do not want fixed energy to be saved.
In the meantime, trendy UEFI motherboards retailer settings on flash reminiscence or on the pc’s arduous disk drive. No battery is critical on these techniques, however you may usually discover it anyway.
What Is UEFI?
The Unified Extensible Firmware Interface (UEFI) specification was launched to supplant BIOS. An industry-wide commonplace agreed upon by chip producers Intel and AMD, together with Microsoft and PC producers, UEFI improves on BIOS.
Attributable to having its roots within the Nineteen Eighties IBM-compatibles period of private computer systems, BIOS has some limitations. UEFI overcomes these, including, for instance, help for drives of two.2TB or bigger, 32-bit and 64-bit modes, and Safe Boot.
This final function is a technique of securing the PC. Safe Boot ensures that malware doesn’t exploit a pc’s boot course of. It does this by checking that any code executed at boot has a sound digital signature. Our in depth take a look at UEFI and the way to disable it for twin booting explains additional.
Different options of the UEFI embody boot choice, overclocking, and configuring varied motherboard-specific settings.
What’s a BIOS?
As an alternative of UEFI, older computer systems use a BIOS, or Primary Enter/Output System, saved in a chip in your pc’s motherboard.
When your pc boots up, the BIOS begins up, performs a power-on self-test (POST), and initializes the pc’s {hardware}. The BIOS then passes management over to a boot loader, often in your arduous drive. (A boot loader may also boot from a USB machine or optical disc.)
The boot loader then hundreds your working system—Home windows, Linux, macOS, or no matter. The BIOS is accountable for low-level system duties. You’ll be able to enter your pc’s BIOS settings display screen by urgent a key throughout boot.
The BIOS settings display screen permits you to configure low-level settings to your pc’s {hardware}. These differ throughout motherboard producers, however some choices are common. An instance is altering the pc’s boot order—the order wherein the pc hundreds working techniques from linked storage.
Intel intends to exchange BIOS with UEFI on all chipsets by 2020.
Why Your Motherboard Wants a Battery
So, if many computer systems retailer BIOS settings in non-volatile reminiscence, why do motherboards nonetheless include batteries? Easy: Motherboards nonetheless embody a Actual Time Clock (RTC).
Energy the pc on or off—the battery runs on a regular basis. The true time clock is actually a quartz watch, like an outdated wristwatch.
When the pc is off, the battery offers energy for the true time clock to run. That is how your pc all the time is aware of the right time whenever you energy it on.
When Is it Time to Exchange Your Motherboard Battery?
As everyone knows from expertise, batteries do not final endlessly. Finally, a CMOS battery will cease working; they usually last as long as 10 years.
Common use of your pc means the CMOS battery lasts longer. Conversely, a battery in a pc that’s principally powered-off will die sooner—it’s utilizing the battery extra, in spite of everything.
If the battery fails on an older pc that shops its BIOS settings in CMOS, you may see error messages like:
- CMOS Battery Failure
- ACPI BIOS Error
- CMOS Learn Error
- CMOS Checksum Error
- New CPU Put in
This final one is especially complicated at first, however the rationalization is easy. With no battery powering the BIOS, the motherboard cannot do not forget that the CPU was already put in beforehand. As such, it thinks it is new each time you boot your pc.
On a more moderen pc that shops its BIOS settings in non-volatile reminiscence, the pc could boot usually, however the pc could cease preserving observe of time when it is powered off. This may result in connection points and issues downloading updates, so it’s price fixing.
The best way to Exchange the Motherboard’s CMOS Battery
To repair these issues, you may want to exchange the CMOS battery, a small, silver disc positioned on the motherboard. Normally a CR2032 battery, it is also utilized in calculators, watches, and different small digital units.
Earlier than continuing, you must energy off your pc, take away the facility cable, and if utilizing a laptop computer, disconnect the battery. Take care to observe commonplace PC upkeep steps when opening your PC and watch out of static electrical energy
Be aware that the battery could also be soldered onto the motherboard in some computer systems. This can require a whole alternative of the motherboard or a restore carried out by the producer.
Pull the CMOS Battery to Troubleshoot PC Points
Eradicating and re-inserting the CMOS battery (often called “pulling”) might also be used as a troubleshooting step on older computer systems.
For instance, if a pc has a BIOS password, eradicating and changing the CMOS battery will wipe the password. Be aware that the opposite BIOS settings will even be wiped, nevertheless.
(If the pc shops its password in non-volatile reminiscence, this may not assist. You would possibly in any other case discover a technique to reset the password utilizing a jumper on the motherboard.)
You may also reset the BIOS settings from inside the BIOS, assuming the pc is booting correctly. Search for an possibility named Clear CMOS or Reset to Defaults.
That is Why Your Motherboard Has a Battery
So, now you already know why there’s a battery in your motherboard:
- On older techniques, the CMOS battery retains the BIOS settings
- For more moderen machines, the CMOS battery powers the PC’s clock
Changing the CR2032 battery in your motherboard is simple, though in some circumstances they’re fastened to the motherboard. Fortuitously, CR2032 batteries are simple to return by, so alternative should not be a difficulty.
Here is one other frequent battery sort you have in all probability used however not know the identify of: the 18650 battery.
Picture Credit score: amphoto/Depositphotos
