In the past it was possible to have the computer's hardware clock in UTC using the following setting
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\TimeZoneInformation]
"RealTimeIsUniversal"=dword:00000001
With Windows 8.1 this settings seems to be ignored.
How do I set the hardware timer to UTC?
(a similar question was asked ages ago in http://social.technet.microsoft.com/Forums/windows/en-US/8b7ce360-a9b1-4358-84cb-3559b063b1d2/windows-7-internet-time-update-and-realtimeisuniversal-utc-registry-hack?forum=w7itproinstall )