[ntp:questions] high jitter on serial gps causes big time offsets

unruh unruh at invalid.ca
Sat Apr 13 23:24:10 UTC 2013

On 2013-04-13, website.reader3 at gmail.com <website.reader3 at gmail.com> wrote:
> On Saturday, April 6, 2013 4:18:33 AM UTC-7, Charles Elliott wrote:
>> I would test the local clock before relying on it for time.  In the bad old
>> days, around year 2000, when I first started processing SETI at Home (S at H) work
>> units (WUs), I could actually see that WUs were being processed faster in
>> the cool early morning hours than they were in the hot afternoons.  The
>> caveat is that an Intel tech support rep denied that that was possible.  In
>> any case, many others have commented on this list that the timing crystals
>> installed in typical motherboards vary significantly with temperature.  If
>> you price timing crystals with guaranteed accuracy you may well believe that
>> they don't install them in typical motherboards; they cost at least as much.
> I can obtain some precision crystals (+/- 2ppm) for about $8 to $10, so why aren't they being added to the mid-level and up motherboards?

Because $8-10 is expensive. 

> It is disgusting to buy a motherboard, load it with graphics processors, and memory and then find that the whole thing cannot keep time.  I consider time keeping THE most neglected component in computer motherboards today.

so run ntpd or chrony. They can keep those motherboards running at
microsecond accuracy, with only the addition of a $35 gps receiver. 

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