If you’ve ever entered the BIOS menu at startup, you will have noticed that one of the settings you can change or set is the system time. The local clock keeps this time in your motherboard powered by the CMOS battery, and you can set it to be whatever you want.
BIOS time is usually set to be the local time for legacy reasons. Even though your operating system will probably sync with a time server to get the accurate time for your system once everything has loaded up and you’re connected to the internet, you should still set an accurate local time on your BIOS.
This is for a few different reasons. For example, if your machine is connected to a local network and your BIOS time is out-of-sync with the rest of the machine in the network, it can cause an issue. Some users have also found that having an inaccurately set time or date in BIOS can cause errors during installation of OS in their freshly minted machines.
Some motherboards allow you to program it to wake the computer up at a certain time. How would the motherboard know when to wake up the computer without the BIOS time?
And lastly, for the very few people out there who are living in areas with intermittent to no internet access, the BIOS time does the primary time-keeping.
Setting the BIOS Time
You will need to boot into the BIOS menu to perform this action. You can load the BIOS menu either directly from the boot screen or let Windows know that you’d like to load into BIOS and restart. If you’re not sure how to perform either action, please refer to this article.
Once you’ve managed to enter BIOS menu, the location of the option to set or change BIOS Time and Date will vary depending upon your device manufacturer. Don’t be afraid to explore the various menu options for a bit until you have found the menu with Time and Date settings.
Once you’ve found it, select the BIOS Time option. If your bios menu has mouse disabled, look at the bottom of the page where there should be an instruction on how to make a change to the system time and follow it.
Setting the BIOS Time On Your Mac
You do not get the traditional BIOS menu options in a Mac machine as you would in a Windows / Linux machine. In order to set BIOS time, you would set the time normally from inside the Mac OS and this will also automatically update your BIOS time.
- Click Apple Menu > System Preferences.
- Click Date & Time.
- Click the lock icon near the bottom-left corner, then input credentials when prompted.
- Uncheck Set date and time automatically
- Use either the Clock or the Digital Display above it to change the time.
What is the Last BIOS Time?
Unlike that Tom Cruise movie, no, this is not the story about when BIOS Time made its valiant last stand. Even though it sounds similar to BIOS time, the last BIOS Time does not even indicate the clock. It’s simply the time it took for BIOS (or more accurately, the UEFI firmware) to initialize your hardware and finish conducting the Power On Self Test (POST). In simpler terms, the last BIOS time indicates the time it took between you pressing the power button and Windows to start loading.
Generally speaking, a sub-10 second Last BIOS Time is preferred. You can check your system’s last bios time by opening the Task Manager.
- Press Ctrl + Shift + Esc to open the Task Manager.
- Switch to the Startup tab.
- Your system’s last BIOS time should be indicated near the top-right corner.
CMOS Date/Time Not Set Error
If you’re getting this message, then your CMOS battery is running out of juice.
Please follow these steps to replace the CMOS battery:
- Power off your PC. Make sure you are wearing an anti-static wristband.
- Open your device casing and find the CMOS battery in the motherboard.
- Carefully, remove the CMOS battery.
- Replace with a brand new battery.
- Put back the casing and power on the device.
- Boot into the BIOS menu and set the current Time and Date.
How Do I Set the Date and Time on My Computer Automatically?
To set Date and Time on Windows automatically:
- Press Win + R and type in
- Switch to Internet Time tab and click on Change settings.
- Put a tick mark on Synchronize with an Internet time server, select a server from the drop-down menu and click Update now.
Et voilà! You don’t have to worry about your PC’s time anymore.
How Do I Check BIOS Date From Windows?
To check the date you have set on BIOS without booting into BIOS menu,
- Press Win + R and type in
- Under System Summary, find BIOS Version/Date field on the right. This should have the current BIOS date listed.