time in OSX after windows

Discussion in 'Windows, Linux & Others on the Mac' started by Craiger, Oct 8, 2007.

  1. Craiger macrumors 6502a


    Jul 11, 2007
    Every time I reboot from xp into mac osx, my time changes, and it does not correct until I open up date and time. I don't have to do anything in "date and time" I just have to open it up. Any suggestions? I would hate to have to do this every time I boot back to OSX.
  2. ilkevinli macrumors 6502


    Apr 8, 2006
    The short solution for people who know how to edit the registry:
    A DWORD key called HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\TimeZoneInformation\RealTimeIsUniversal needs to have the value of "1"

    The step-by-step solution is as follows:

    1. Boot Windows

    2. Click Start --> Run and type regedit. Click OK

    3. The Windows Registry Editor should pop up. Navigate within the explorer to:

    4. Click on the TimeZoneInformation "folder" from the navigation pane if you haven't already done so.

    5. This assumes the correct key doesn't exist. If it does, you will just change the existing key's value: Right click on the white space within the folder (If you don't have a right mouse button, you may need to download a program called applemouse to emulate the "control-click" of the apple 1-button mouse). Select new --> DWORD Value. Title the key "RealTimeIsUniversal" (No quotes). Set the value to "1" (No quotes again). Hexidecimal should be fine.

    6. Either reboot and set the clock in MacOS or set the clock in Windows. You should now be able to reboot into either OS and have a correct clock.

  3. Craiger thread starter macrumors 6502a


    Jul 11, 2007
  4. Eidorian macrumors Penryn


    Mar 23, 2005
    I've found that Windows' Internet Time works just fine as well.
  5. Craiger thread starter macrumors 6502a


    Jul 11, 2007
    This worked! Thank you.
    if you don't mind, could you quickly explain what the problem was, in layman terms. I am just curious.

    Thanks again!
  6. hob macrumors 68020


    Oct 4, 2003
    London, UK
    Off the top of my head:

    Windows stores system time as local time - for me that means it adds one hour to the system time for BST (GMT+1) every time I reboot.

    Mac OS X as well as every other OS in the world stores system time as GMT. So when you load OS X, it checks system time, which Windows will have changed to be whatever your local time is. It will assume that that is GMT, then add or subtract your local time zone...

    The registry changes you've just made are something carried over from Windows NT - presumably someone in Microsoft wanted to make Windows standardised, but it was never fully implemented.
  7. Craiger thread starter macrumors 6502a


    Jul 11, 2007
  8. Consultant macrumors G5


    Jun 27, 2007
    I did this awhile ago and it seems to work until recently.

    Anyone else has problems with it? Running 10.4.11, but I installed the Leopard bootcamp drivers.
  9. jeamland macrumors newbie

    Nov 15, 2006
    so this works fine, everything's AOK

    but apple installs something that periodically sets the time and makes it "smart" to re-adjust it.

    in other words, the apple software ignores the realtimeisuniversal setting in the registry.

    anyone know how to disable the apple time checking thingy?

    (in other words, it works and everything seems fine, and then when apple's periodic "fixit" program runs, it breaks again.)
  10. jeamland macrumors newbie

    Nov 15, 2006

    After setting the "RealTimeIsUniversal" setting as above, go into services (manage computer -> services or control panel -> administrative tools -> services) and select the "Apple Time Service" and set it to DISABLED. this will prevent apple from being "smart" :)
  11. coohou macrumors newbie

    Feb 18, 2008
    Thanks a lot for the info. It was very helpful.
  12. ryannazaretian macrumors 6502a


    Sep 21, 2008
    We should sticky this, because Microsoft isn't going to fix this.
  13. mBox macrumors 68020

    Jun 26, 2002
    Thanks jeamland and everyone else that contributed.
    This was very helpful :)
  14. najeebanwer macrumors newbie

    Dec 13, 2011
    Bug in Windows 7 Wake Timers when RTC = UTC

    The registry key HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\TimeZoneInformation\RealTimeIsUniversal when set to the DWORD value = 1 indicates that the RTC is set to UTC.

    This works properly, in that Windows 7 correctly sets the time according to the Time Zone information provided, except that apparently the WAKE TIMERS (powercfg -waketimers) are not configured properly and will wake up the computer at the wrong time or not at all (if, for example, the wake time has already passed in UTC terms).

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