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time in OSX after windows

Craiger

Craiger

macrumors 6502a
Original poster
Jul 11, 2007
852
305
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.
 
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:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\TimeZoneInformation

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.

Craiger said:
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.
Click to expand...
 
ilkevinli said:
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:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\TimeZoneInformation

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.
Click to expand...

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!
 
Craiger said:
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!
Click to expand...

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.
 
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.
 
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.)
 
SOLUTION:

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" :)
 
jeamland said:
SOLUTION:

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" :)
Click to expand...

Thanks a lot for the info. It was very helpful.
 
ilkevinli said:
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:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\TimeZoneInformation

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.
Click to expand...

We should sticky this, because Microsoft isn't going to fix this.
 
jeamland said:
SOLUTION:

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" :)
Click to expand...
Thanks jeamland and everyone else that contributed.
This was very helpful :)
 
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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