[ntp:questions] Clock skew changes drastically between reboots
root at localhost.invalid
Sun Apr 1 18:44:38 UTC 2007
I've noticed something I find very strange on the systems I have to work
with. Every time I reboot the computer, the clock skew of the local
clock changes, sometimes by what seems to be a huge amount.
For example, I boot the computer, let ntpd run for 12 hours, and the
value recorded in the drift file is 35 ppm. I reboot the computer, let
ntpd run for 12 hours, and I get 5 ppm...
The temperature in the room did not change much. Could the operating
system (Linux 188.8.131.52-rt8) be responsible for this? Could the
motherboard supply a different voltage every time I reboot the system?
How much is the system clock in a PC affected by temperature? I've read
2 ppm per °C, or was it 0.5 ppm per °C? How much is it affected by
voltage? What other parameters have an influence?
When I say "system clock" I think that, on this system, Linux uses the
PIT on the motherboard, but I'm not 100% sure.
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