[ntp:questions] Re: Help needed with excessive drift

Richard B. Gilbert rgilbert88 at comcast.net
Fri May 6 01:55:25 UTC 2005


mlawdawg at yahoo.com wrote:

>I appreciate your comments. However, that's not my understanding from
>the documentation (ntpd.html & misopt.html) The docs state that the
>"step threshold" defaults to 128ms. If an adjustment is needed that's >
>than the step threshold, the clock is stepped. Otherwise, it's adjusted
>or "slewed" (per source comments). The panic threshold defaults to
>1000s. If an adjustment is needed > than the panic threshold, ntp will
>exit. The -g does prevent's the panic check on the initial adjustment.
>Also, from watching ntpd behavior, it sets my clock correctly when the
>first adjustment is ~200secs. That's well under the panic threshold of
>1000s.
>
>  
>
It sounds as if your hardware may be out of tolerance.   The crystal 
oscillator that drives the system clock must be within +/- 500 parts per 
million of the correct frequency.   That frequency tolerance translates 
to something like +/- 48 seconds per day.   Most computer hardware falls 
within this tolerance range.   If yours does not, ntpd is not going to 
work properly!

It is sometimes possible to tune the crystal oscillator by connecting a 
trimmer capacitor across the crystal and adjusting the capacitor while 
measuring the frequency of the oscillator.   Doing so will probably void 
the warranty on your motherboard.   If it's out of warranty or you don't 
care about voiding the warranty and if  you have the necessary skills 
and test equipment (frequency counter) you might want to give this a 
try.   The only other options I can think of are to ask the manufacturer 
to repair the motherboard or to replace the motherboard.    Some 
manufacturers might actually do it! :-)



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