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danilopiazza's avatar
danilopiazza
Copper Contributor
Jan 09, 2026

Downsides of using UTC time by setting RealTimeIsUniversal

Hi,

I have a dual-boot machine where I use both Windows 11 and Linux.

To fix a minor annoyance with the hardware RTC clock always being set to the wrong time zone whenever I switch to the other OS, I know I can make Windows use UTC time by adding the RealTimeIsUniversal entry to the registry:

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

What are the downsides of making this change?

Are there any known issues, other than the usual caveats about using undocumented and unsupported registry keys?

configuration

1 Reply

  • CalahanReed's avatar
    CalahanReed
    Iron Contributor
    Jan 14, 2026

    Setting RealTimeIsUniversal to 1 tells Windows that the hardware clock is set to UTC, aligning it with Linux's expectations.

    When this is enabled, Windows will interpret the hardware clock as UTC rather than local time.

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