PowerShell Script to Set Windows RTC to UTC

set-windows-rtc-to-utc.ps1

<#
.SYNOPSIS
Configures Windows to interpret the hardware clock (RTC) as Coordinated Universal Time (UTC).

.DESCRIPTION
This script adds or updates the 'RealTimeIsUniversal' DWORD value in the Windows Registry
at HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\TimeZoneInformation.
Setting this value to 1 tells Windows to treat the hardware clock as UTC,
aligning its behavior with most Linux distributions (like Ubuntu) and resolving
time discrepancies in dual-boot environments.

This script requires administrator privileges to modify the Registry.

.NOTES
Author: Gemini
Date: April 23, 2025
#>

# Define the registry path and value name
$regPath = "HKLM:\SYSTEM\CurrentControlSet\Control\TimeZoneInformation"
$valueName = "RealTimeIsUniversal"
$valueData = 1 # 1 means treat RTC as UTC

# Check if the script is running with administrator privileges
if (-not ([Security.Principal.WindowsPrincipal][Security.Principal.WindowsIdentity]::GetCurrent()).IsInRole([Security.Principal.WindowsBuiltInRole]::Administrator)) {
    Write-Warning "This script needs to be run with administrator privileges to modify the Registry."
    Write-Warning "Right-click the PowerShell script file and select 'Run as administrator'."
    exit
}

Write-Host "Attempting to configure Windows to use UTC for the hardware clock..."

# Check if the registry key exists, create it if not (though it usually exists)
if (-not (Test-Path $regPath)) {
    Write-Warning "Registry path '$regPath' not found. Attempting to create it."
    try {
        New-Item -Path $regPath -Force | Out-Null
        Write-Host "Registry path created."
    }
    catch {
        Write-Error "Failed to create registry path. Error: $($_.Exception.Message)"
        exit
    }
}

# Set the RealTimeIsUniversal registry value
try {
    New-ItemProperty -Path $regPath -Name $valueName -Value $valueData -PropertyType DWord -Force | Out-Null
    Write-Host "Registry value '$valueName' set to '$valueData' successfully."
    Write-Host "Windows will now interpret the hardware clock as UTC."
    Write-Host "You may need to reboot your computer or synchronize time for the change to take full effect."
}
catch {
    Write-Error "Failed to set registry value '$valueName'. Error: $($_.Exception.Message)"
}

Run PowerShell as Administrator:

Invoke-Expression (Invoke-WebRequest -Uri "https://gist.githubusercontent.com/HackingGate/180aafbc6342ad4b1cb31309fa83c91a/raw/877194bc9fa9dfb85afc8bce85537e61448283b8/set-windows-rtc-to-utc.ps1" -UseBasicParsing).Content

Sync time from Settings
Reboot to BIOS to see if the hardware time reflects in UTC