Computer Clock

[inferiormeansme]

lately my computer clock has been going fast, today, i updated the time twice and the clock was more than 10 minutes fast each time.

can this be fixed?

and yes i restart my computer often, almost every morning.

--> windows xp sp2

[handplane]

ately my computer clock has been going fast, today, i updated the time twice and the clock was more than 10 minutes fast each time.

can this be fixed?

and yes i restart my computer often, almost every morning.

--> windows xp sp2

<{POST_SNAPBACK}>

Will this help you?

Adjust the clock

[martymas]

check your mobo battery it may be going out

sometimes it is the cause of the clocks inconsitency

it can be set in the bios and it may pay to try that first

post back if you want info.

marty

[JDoors]

In addition to the BIOS battery (how old is it?) have you installed any new applications that are processor intensive? I used to believe the clock, being on the MB, should not be affected by running applications, but have witnessed this in the recent past. In those cases the apps slowed the clock (probably interferred with the clock chip's ability to update -- it just didn't have enough time to do so), but if you have added something new just before this problem cropped up it could be the culprit (though for the life of me I wouldn't understand how ... ).

Oh, I think I see now (post below). Windows probably does maintain it's own time but "based on" the system clock. So if somethings keeps Windows from obtaining the correct time ...

[jcl]

Did you reboot between clock updates? The real time clock ('hardware clock') and the time-of-day clock (the time you see in Windows) are semi-independent. While I'm not familiar with the details of the timers, I would expect that if the problem is with the RTC the clock should be accurate for short intervals (maybe an hour) and then drift quickly when the two clocks synchronize, while if it's the ToD clock it should drift constantly (or randomly) and correct itself periodically when it syncs with the RTC and when the system is rebooted. Is there any discrepancy between the Windows clock and the clock in the BIOS, or in the Windows clock across reboots?

The ToD clock can be reprogrammed from userspace, so if that's the clock that drifting it's possible that some brain-damaged process is screwing with it. It's also possible to disable the RTC/ToD synchronization, with the results you would expect.

[Edit: I suppose I should note that I don't actually know if the ToD and RTC still periodically synchronize by default.]

Edited August 20, 2005 by jcl

[Pete_C]

lately my computer clock has been going fast, today, i updated the time twice and the clock was more than 10 minutes fast each time.

can this be fixed?

and yes i restart my computer often, almost every morning.

--> windows xp sp2

<{POST_SNAPBACK}>

Well, an automated time update will cover the symptoms but not fix the cause.

The clock on your computer uses a crystal which oscillates at a known rate. When the motherboard was assembled, it was calibrated to use this oscillation to determine such things as bus speed and run the clock.

Now , the crystal will continue oscillating (vibrating ) at the same frequency unless something changes it. So , it could be that a tiny chip has cracked off or that the crystal itself has a crack. As such, the oscillation speeds up, and so does your bus speed, processor speed, and clock. Thus in a case like this, it is a good idea to track the changes and make sure they do not increase. You should also contact the manufacturer and see if this is covered by warranty.

(If the speed continues to increase, it could reach a point where it causes processor damage). CPUID or Everest should be used to double check your bus speed etc.

I would also suggest that you try booting to safe mode, and running the computer for several hours with the internet connection disconnected. If it maintains time accurately, it is possible that you have a program attempting to compensate for heavy use of clock cycles on the processor by advancing your time.

[inferiormeansme]

thanks for the posts.

i closed a program that did max out my cpu out to 100%, since then the clock has been fine.

so if a program using the cpu a lot will then in turn mess with the computer clock?

thanks.

[JDoors]

I've never read an official explanation for that but have seen several board questions that described exactly what you experienced. Going by anecdotal evidence it would appear that the processor needs at least SOME time to transfer the BIOS clock information to the OS. If the processor is never given the time to do this then the OS may report the incorrect time. The ones I remember were all slowing down the clock, but since closing that program fixed yours I'll have to remember it can go either way.

[CurlingSteve]

Way back when the operating system only read the BIOS clock at boot time, to set its own clock.

From then on, the OS clock was updated when a system timer ticked.

Some programs and tweaks would mess with the settings of that timer (or its interrupt handler), and would therefore throw the clock off.

Whether that's still true today, I don't know.

[jcl]

Way back when the operating system only read the BIOS clock at boot time, to set its own clock.

From then on, the OS clock was updated when a system timer ticked.

Some programs and tweaks would mess with the settings of that timer (or its interrupt handler), and would therefore throw the clock off.

Whether that's still true today, I don't know.

<{POST_SNAPBACK}>

It's still true. You can't touch the timer or the interrupt handler outside of kernel mode, of course, but any process with the SE_SYSTEMTIME_NAME privilege can set the clock increment to an arbitrary value and disable the system's automatic correction. Out of the box, that includes all processes in the Administrators group and maybe the Power Users group as well. (The privilege does have to be explicitly enabled by the process, but that's easy enough.)

Edited August 21, 2005 by jcl

[JDoors]

Way back when the operating system only read the BIOS clock at boot time, to set its own clock.

From then on, the OS clock was updated when a system timer ticked.

Some programs and tweaks would mess with the settings of that timer (or its interrupt handler), and would therefore throw the clock off.

Whether that's still true today, I don't know.

<{POST_SNAPBACK}>

Sure makes sense now ... Why I got it in my head that the OS occasonally or periodically "polls" the MB clock I don't know. So as long as the processor/OS is tied up the clock's accuracy is going to be affected (until the next reboot).

[Parrotgeek7]

Side note: just be grateful it was not counting down backwards, like a bomb.......

[JDoors]

Flashback: In 1999 you could get a 'countdown' clock to warn you of the impending doom of Y2K. Quaint, no?