Dual boot Linux and Windows – BIOS system time incorrect

I, unfortunately, have to dual boot to Windows once and a while, due to requirements where I currently have an assignment.

What I’ve noticed and that really grind my gears, is that when booting Windows after I have been running Linux the BIOS System time is incorrect by -2 hours.

After searching for information how to solve this, I found a thread on the Microsoft forum with a user that had the same problem and learned something new:

Windows uses BIOS time to hold ‘local’ time (UTC+offset+daylight savings according to the time zone used) and Linux uses BIOS time to hold Universal Time (UTC).

That got me to the ever so good Arch Linux Wiki (this is an area that I think Ubuntu has become weaker in; updated and good information in a community wiki. Don’t get me wrong, I love askubuntu.com).

Open Windows Powershell and run it as administrator:

reg add "HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\TimeZoneInformation" /v RealTimeIsUniversal /d 1 /t REG_DWORD /f

If this does not solve it, try changing REG_DWORD to REG_QWORD.

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