OfficerJackMehoff Posted June 30, 2009 Share Posted June 30, 2009 I have noticed that for some reason, OS X treats my CMOS clock as though it were Greenwich time or something (+0:00) b/c when I boot into OS X and it auto corrects the time, my clock is 5 hours off when I boot back into Windows. I have to set it to Guam time for things to be correct. I've always used chameleon bootloader, perhaps that has something to do with it? If so, what do I do about it? Link to comment https://www.insanelymac.com/forum/topic/172926-os-x-and-cmos-timedate/ Share on other sites More sharing options...
LoneWaffle Posted June 30, 2009 Share Posted June 30, 2009 It is not a result of Chameleon, it is OS X itself. I had a hard time believing it when I first got into this. I thought "How could OS X be changing my BIOS time when real Macs don't even have a BIOS?" But it's true. Mac OS keeps the BIOS time in Greenwich time (universal time). Most Unix based operating systems behave this way. There is a registry key that can be modified in windows to correct this, but I've found that method doesn't work reliably. I'd restart my computer and still have the same problem from time to time. It seems a better solution is here: http://www.swmirror.org/drupal/?q=node/32 Good luck. Link to comment https://www.insanelymac.com/forum/topic/172926-os-x-and-cmos-timedate/#findComment-1188723 Share on other sites More sharing options...
Chrysaor Posted June 30, 2009 Share Posted June 30, 2009 It is not a result of Chameleon, it is OS X itself. I had a hard time believing it when I first got into this. I thought "How could OS X be changing my BIOS time when real Macs don't even have a BIOS?" But it's true. Mac OS keeps the BIOS time in Greenwich time (universal time). Most Unix based operating systems behave this way. There is a registry key that can be modified in windows to correct this, but I've found that method doesn't work reliably. I'd restart my computer and still have the same problem from time to time. It seems a better solution is here: http://www.swmirror.org/drupal/?q=node/32 Good luck. MS fixed the RealTimeIsUniversal key with Vista SP2 or 7, its the best method for both OSs. Link to comment https://www.insanelymac.com/forum/topic/172926-os-x-and-cmos-timedate/#findComment-1188788 Share on other sites More sharing options...
LoneWaffle Posted June 30, 2009 Share Posted June 30, 2009 Well, in that case, I guess try the registry method: HKEY_LOCAL_MACHINE \ System \ CurrentControlSet \ Control \ TimeZoneInformation \ RealTimeIsUniversal This is a DWORD registry key that must be created. Setting this value to 1 will tell the Windows OS to consider the system / hardware clock to return time in UTC instead of considering it local time. Link to comment https://www.insanelymac.com/forum/topic/172926-os-x-and-cmos-timedate/#findComment-1189086 Share on other sites More sharing options...
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