Windows 10: How does windows handle a time delta between the OS system time and the BIOS time?

I have a system that is not connected to the internet. It is common to move hard drives between systems. It is common for there to be a difference between the BIOS clock on the motherboard/CMOS and the clock stored on the hard drive and Windows OS. What does Windows do when there is a difference between the hardware motherboard and software Windows OS clocks? Is there a setting that can prioritize which time BIOS or OS is used in the event of a difference? If it exists is it expected that the BIOS/motherboard should have this setting rather than Windows? I was not able to find

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Changing Time Format

Hi Mary,

There's a possibility that the set up time format in your computer Basic Input/Output System (BIOS) is military time. To have this checked, you can try to reset the time of your computer through Control Panel. See the steps below on how to do
so:

• Open Control Panel > Clock, Language, and Region >
  Change date, time, or number formats. This would open the
  Region window.
• From there, click on Additional settings at the bottom part. It will open the Customize Format.
• Click Reset; then, OK.

The steps should work; however, if not, we suggest that you contact manufacturer and have the BIOS time checked.

Let us know what happens after doing the suggestions .

 

Can't able to change the system time

Hi,

If the system time is not changing after configuring the date and time settings on Control Panel, most likely, the BIOS clock is also incorrect. We suggest making sure that the date and time settings on your computer is properly configured. To configure
the date and time settings, follow the steps below:

• In Cortana search, type control panel.
• Choose Control Panel from the list.
• Select Clock, Language, and Region.
• Click Date and Time.
• Click Change date and time, then set the correct information.
• Click Change time zone, then select the correct time zone.
• Click Apply and then click OK.

If the system time still didn't change, we recommend that you contact the computer manufacturer for further assistance on how to check and configure the BIOS clock of your device.

Feel free to post back if you have other concerns.

 

windows time and internet time does't sync

That's because Windows and Ubuntu use internal clock in BIOS differently.

When Windows get time from internal clock it handle it as local time, but Ubuntu (or mac OS in my case) handle that time as UTC time.

I correct this by changing way how Windows handle that time as UTC, but you can also set Ubuntu to handle that time as local time.

To set Windows use UTC make following setting to registry: (Set UTC on)

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\TimeZoneInformation]

"RealTimeIsUniversal"=dword:00000001

Set Windows back to use local time: (Set UTC off)

"RealTimeIsUniversal"=dword:00000000

Set Ubuntu to use local time:

How to Fix Time Differences in Ubuntu 16.04 & Windows 10 Dual Boot | UbuntuHandbook