Windows XP clock runs way too fast.

The Windows clock gets its initial time from the
motherboard when it boots up, but how does the clock keep
accurate time after that?

I'm having a very stange problem with my Windows XP
clock. Sometimes when my computer boots up the Windows XP
clock runs very fast, about 9 minutes too fast after one
hour. Sometimes the clock runs perfectly normal. If I
turn my system on in the morning and it is running too
fast, I have to reset the system once to get the clock to
run at normal speed. The two or three times I've gone
into the bios menu to watch the clock, it was normal and
also, every time I turn my computer on in the morning the
windows xp clock starts out in sync with real time. These
facts would suggest the motherboard's clock is not at
fault.

I'd really appreciate any help on this. It has been very
difficult to find anyone who has even the slightest clue
about this strange problem.

Hi,

In good old dos the hardware clock was only read while starting up. For the
rest MSDOS kept time by increasing its internal counter on every interrupt
from the timer chip.

Still if the timer chip gives it's interrupts too fast the the clock
ofcourse advances too fast.

Usually you can see the time running in the bios screen. If that is the case
just go to the bios screen. Look at the time note the time of a time
reference wait an hour or so and check it again. If it is plus 8 minutes you
know your motherboard has a problem if not my gues would be either a virus
or you selected a ntp time source that is not accurate. (Click as admin on
the time to check)

Regards, Ron AF Greve.

"Dan" <kaminwx@yahoo.com> wrote in message
news:093b01c346ff$78da19b0$a001280a@phx.gbl...
> The Windows clock gets its initial time from the
> motherboard when it boots up, but how does the clock keep
> accurate time after that?
>
> I'm having a very stange problem with my Windows XP
> clock. Sometimes when my computer boots up the Windows XP
> clock runs very fast, about 9 minutes too fast after one
> hour. Sometimes the clock runs perfectly normal. If I
> turn my system on in the morning and it is running too
> fast, I have to reset the system once to get the clock to
> run at normal speed. The two or three times I've gone
> into the bios menu to watch the clock, it was normal and
> also, every time I turn my computer on in the morning the
> windows xp clock starts out in sync with real time. These
> facts would suggest the motherboard's clock is not at
> fault.
>
> I'd really appreciate any help on this. It has been very
> difficult to find anyone who has even the slightest clue
> about this strange problem.
>
>

Dan wrote:

>The Windows clock gets its initial time from the
>motherboard when it boots up, but how does the clock keep
>accurate time after that?

A PC generates a 'timer interrupt' about 20 times a second, and the
clock is maintained by counting these. Clock rates that run steadily at
a big loss or gain are probably because the motherboard/BIOS and Windows
have different ideas on how often the interrupt happen. Small
variations in this are handled when you use the Internet Time sync -
this notes the error and adjusts the assumed interval accordingly, so
that after a few occasions the clock rate is very near right anyway.

Sometimes (especially with Dell machines) the discrepancy is outside
the range that the time sync will adjust - and you get a large steady
error, like 10 minutes in an hour. If that happens Try these steps:

1. Start->Run cmd.exe
2. net stop w32time
3. w32tm.exe /unregister
4. w32tm.exe /register
5. net start w32time

(note spellings w32tm and w32time in different commands)

If you get short term bad clock rates, there *may* be some rogue program
that is preventing the interrupts being handled. This was common enough
in Win98, but ought not to be possible in XP. If it happens note what
you have running at the time, and see if you can identify a program
doing it. System Utility things like Norton would be main suspects

--
Alex Nichol MS MVP (Windows Technologies)
Bournemouth, U.K. Alexn@mvps.org