Can CMOS Battery Cause Computer Not Start?

A CMOS (Complementary Metal-Oxide Semiconductor) is a motherboard component that stores data about your computer’s Basic Input/Output System (BIOS). This memory chip can store data even when the power is off. Therefore, if it fails, the data will be lost, and the computer will not be able to start. When the chip starts to leak, it’s a sign that the CMOS battery is about to fail. In some cases, this issue could be fixed by replacing the CMOS battery, but in others, it requires replacing the entire motherboard.

Will a computer start with a dead CMOS battery?

It depends on the computer. Some computers might start with a dead CMOS battery, while others will not. If your computer does not start with a dead CMOS battery, you need to replace the battery. Check the CMOS battery status indicator on your computer to know if the CMOS battery is low or needs to be replaced. If the indicator says that the CMOS battery is low, you should replace it as soon as possible. A low CMOS battery causes your computer not to start correctly. If your computer does not have a CMOS battery status indicator, you can still check the battery status by looking for a battery icon in the system tray. If this icon is present, double-click it to see the battery status. The battery status will tell you how much power is left in the battery. When the battery reaches a low level, it might be CMOS battery failure symptoms so you should replace and fix CMOS battery failure.

Can PC turn on without CMOS battery?

If your computer is not starting up, it’s possible that your CMOS battery is dead or not working properly. You can test this by removing the battery and seeing if your PC starts up. If it does, you know that the battery is dead and needs to replace it. If it doesn’t start up, then there is most likely a problem with your motherboard. You should consult a computer technician to help diagnose and fix the issue in either case. If your computer is not turning on at all, even when you have the CMOS battery in place, there may even is a problem with your power supply. Try replacing the power supply to see if that fixes the issue.

What happens when the CMOS battery fails?

CMOS battery failure can result in the loss of date and time settings. The computer may not start up or boot into Windows, even if it is okay with the Power Supply Unit (PSU). It could be due to a CMOS battery voltage issue that causes problems like POST errors, operating system crashes, or no display or black screens.

In some cases, the BIOS settings may get corrupted, and you will need to reinstall it. If your computer has a sealed battery, you must have to replace the entire unit. Sealed batteries usually last for around three years.

If you are experiencing any of these symptoms, you should check your CMOS battery first. The CMOS battery varies depending on operating conditions, but most systems have batteries that last anywhere from 18 months to four years before they fail. Some online tools will allow you to discharge and load your battery to see if it is still holding a charge if you are unsure how to test your CMOS battery. Similarly, you can also use a multimeter to measure the voltage of the battery. A healthy CMOS battery should have a voltage of around three volts. If your battery is below this, it’s time to replace it.


It’s possible that a CMOS battery is a culprit behind your computer not starting. It is essential to check the condition of the CMOS battery and replace it if it has run out of juice. CMOS batteries are small and tend to last two years. If your computer isn’t starting, it is important to check the CMOS battery to determine if it needs to be replaced. To avoid this issue, always keep your computer in good condition.

About the author, Phil Borges

Phil Borges is a battery aficionado. He's written extensively about batteries, and he loves nothing more than discussing the latest innovations in the industry. He has a deep understanding of how batteries work, and he's always on the lookout for new ways to improve their performance.