Clock in OSX falls behind after booting out of bootcamp

Discussion in 'Windows, Linux & Others on the Mac' started by ethan86, Jul 22, 2010.

  1. ethan86 macrumors member

    Jul 14, 2009
    As the title says, when I boot out of bootcamp and back into OSX, my clock falls back by 4 hours, but the clock on the windows side (Win 7) is running fine. I've done some searching, but have found little useful information and all the threads I've come across (not just on this site) have been 2-3 years old and didn't have any clear answers. Can anyone help me out with this?
  2. SilentPanda Moderator emeritus


    Oct 8, 2002
    The Bamboo Forest
    I think one OS stores the internal clock as your timezone and the other as GMT. So when booting between the two they basically overrule each other. I don't have a solution, but I'm pretty sure that's why.
  3. ethan86 thread starter macrumors member

    Jul 14, 2009
    That shouldn't be the problem; I have the time zone in Windows and OSX set to EST.
  4. Guiyon macrumors 6502a

    Mar 19, 2008
    North Shore, MA
    That is actually the cause of the issue. Windows assumes your system clock is set to EST and displays it as-is. Mac OS X (and every other sane OS) assumes your system clock is set to GMT and adjusts the displayed time to match your TZ setting. If you have the Bootcamp drivers installed this *should* fix the issue but sometimes it doesn't. You could also set the "HKLM\SYSTEM\CurrentControlSet\Control\TimeZoneInformation: RealTimeIsUniversal" key to "1" in the registry and that should help.
  5. ethan86 thread starter macrumors member

    Jul 14, 2009
    Alright, I'll change that registry key when I get home tonight and if that doesn't work, I'll reinstall the drivers.
  6. HadItWithWindow macrumors regular

    Dec 1, 2008
    My OSX clock is fine, it's Windows 7 that displays incorrect

    So, reinstall drivers. From where? Mac OS or Windows 7?

    I use bootcamp and when folks advise me to install drivers for windows7 I'm never certain WHICH operating system I should be in and WHICH disk for drivers.

    In other words if my Windows7 clock is always off (it is) do I use drivers for OSX while booted in Windows??

  7. yellow Moderator emeritus


    Oct 21, 2003
    Portland, OR
    The regkey fix works for the time differential between Mac OS X and Windows.

Share This Page