So my Windows 8 installation, in boot camp on MacBook Air, started to have this issue whenever I woke from sleep the time would jump forward 10 minutes, eventually throughout the day the computer may go back to the correct time. However if the time was already wrong it wouldn’t change on wake from sleep.
My time was set to sync with an internet source, selecting ‘Update Now’ would always revert Windows to the correct time:
Normally on Windows Running via Bootcamp the time is kept in sync with the Apple Time Service which I had disabled
I had disabled it because it was unnecessary to keep time in sync via service, but rather Windows could be configured to use “Universal Time” In the past this had always worked…
This had been accomplished by setting RealTimeIsUniversal to 1 under HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\TimeZoneInformation
Re-enabling the Apple Time Service didn’t fix the issue.
Looking to Windows Event viewer I filtered by events in System log from Kernel-General and of Event ID 1.
Here we could see the reason for the time change:
The system time has changed to 2013-06-11T08:36:59.500000000Z from 2013-06-11T08:26:56.716112600Z.
Change Reason: System time synchronized with the hardware clock.
So I suspected changing the time in Windows was not updating the Macs hardware clock. This was proved by booting into MacOS – and the time was wrong. I configured the time in MacOS to Set date and time automatically, and the time was immediately corrected. Restarting Windows had the right time now…no more unexpected time changes