Is not there, if it is type bcdedit /deletevalue useplatformclock to remove it and then reboot Windows. Open administrator cmd.exe and type bcdedit /enum and then make sure useplatformclock Check the section titled Tuning the Guest Additions time synchronization parametersįirst make sure Windows is not restricted to use HPET only as this may prevent the host and guest(s) to get an accurate RTC source: You should restart your guest additions service or your guest machine in order for it to take effect. You can configure the guest -timesync-set-threshold from the host machine using the following command: VBoxManage guestproperty set '/VirtualBox/GuestAdd/VBoxService/-timesync-set-threshold' 1000 You could for example set it to 1000ms, so you should never find a machine with a difference above one second. It is possible to change the 20 minute threshold using the -timesync-set-threshold guest parameter. Thus you should never find a machine out of sync more than 20 minutes. This service corrects the clock drift every 10 seconds if the difference between the host and guest clock is below 20 minutes, if the difference is above 20 minutes it just resets the guest clock to the host time. If you have installed VirtualBox additions (and you probably have) there is a service on the guest host that syncs the time.

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