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erratic clock behaviour in Windows XP

doublehorn asked
Last Modified: 2012-05-04
I administer a Dell Dimension P4 desktop running Windows XP Pro, SP1. This computer, like 5 others on the same subnet, is acquiring an NTP/GPS time signal via Tardis Time Server (running as a service). Occasionally, but with increasing frequency, this system clock on this machine becomes uselessly erratic. This erratic behaviour seems to fall into one of two categories:

1.) the clock spins forward at a rate of 15 sysclock minutes: 1 real second.
2.) the clock spins backward at a rate of 5 sysclock seconds: 1 real second.

This computer runs client software for a 911 Emergency Dispatch CAD system, so the accuracy of the timestamp of data sent from this computer to the CAD server is fairly important for legal purposes. Obviously, the timestamp of the data sent from this problem machine is worthless when the clock is behaving this way - which, these days, is at least once a week. A reboot usually resolves the problem for a period, but since this machine needs to be on and operational 24/7 (911 dispatch business requirement), rebooting in the middle of a 911 call is not always an option.

I see one of 3 options:

1.) some sort of NTP clock-variation suppressing software, that suppresses variations in time above a certain threshold, say 500ms.
2.) install some sort of monitoring tool to see if there is some specific circumstance that might cause a clock to behave in this way.
3.) buy a new computer - not really a feasible option, since Dispatch guys just bought this computer and probably couldn't make an argument for buying yet another.

There are 2 identical Dell Dimensions running the same suite of software on the same subnet off the same NTP time signal that are behaving just fine, so I've ruled out ambient heat or some other digital or physical environmental condition. I've tried a few shareware monitoring and suppressing utilities, but so far haven't found anything that is really helpful. Any thoughts, I'm all ears.

doublehorn - from the not-quite-so-frozen wilds of Southern BC.
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Fatal_ExceptionSystems Engineer
Top Expert 2005

Try replacing the battery on the motherboard first..  An inexpensive solution to an otherwise drastic problem..
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I think your best bet is to check with Dell.  If you "just purchased" this one, they'll most likely send someone up for free on-site service.  Or just threaten to return the unit for replacement.

I don't think it is a battery issue.  Usually the batter is used to keep the bios and/or clock when the computer is off.  It should affect the outcome of the clock when the computer is turned on.

I don't think the automic clock sync would help either.  If what you said was true, then this problem occurs while the computer is running.  Which means that you may have synchronized your clock 3 hours ago, but it could just go off on you... and setting the computer to sync on a minute-by-minute bases isn't a real option.

I think this could either be a hardware issue or a software glitch.  Perhaps you should ask Dell and see what they think.  Let them know that you're calling from a 911 dispatcher, because I'm sure they don't want to be blamed for a system foul-up during an emergency 911 situation :-P

- Info
Fatal_ExceptionSystems Engineer
Top Expert 2005

Very true info..  just that replacing that battery could (emphasize could) be a $4 solution..  And letting Dell know that this is for 911 dispatch purposes is excellent..  They will definitely be more helpful if they know that..  


Sorry about the delay in awarding points for this question. The intermittent nature of the problem dictated that I needed to see several weeks of stable behviour before calling the problem resolved.

LRI41's suggested that Dell had issued a patch to correct some system clock weirdness which I downloaded from Dell and applied. In the weeks since I've applied the patch, the clock has been 100% stable and accepts its time from the NTP time signal as reliably as the rest of the 911 workstations in the Dispatch Centre. While I'm going to maintain a high degree of skepticism about the fix, it seems like this actually worked. All 250 Points go to LRI41.
Fatal_ExceptionSystems Engineer
Top Expert 2005

Very good..  Kudos to LR for finding that fix..


Nothing brillant about it, I boughty a Dell for myself and my two sons a couple of years ago, and myself and one son had clock problems until we applied this fix.  Now my runs almost perfectly, mayby gets a second or so behind every 6 or 8 months.

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