[time-nuts] NTP and Windows 7

Brian Inglis Brian.Inglis at SystematicSw.ab.ca
Thu Mar 27 11:51:55 EDT 2014

On 2014-03-27 07:59, John Nelson wrote:
> Greetings from Wales. I'm not sure whether this august forum is the
> appropriate place to ask a question about PC timekeeping, but in the hope
> that someone can point me in the right direction I'll ask anyway ;-)
> I have just replaced Windows XP with Windows 7. The PC involved (a fairly
> elderly 2.4GHz Core2 machine) runs an application called 'PlanePlotter'
> which requires accurate timekeeping and mandates Meinberg's NTP software.
> Using the UK pool.ntp.org servers as a reference source this has worked very
> well under XP for several years and the clock was seldom more than a few
> milliseconds out. Under Windows 7, however, the clock can be anything up to
> 0.2s awry and the offset is very erratic. The daily loopstats graph looks
> like a section through a mountain range.
> I have carefully checked all settings and combed the internet for
> suggestions but can see no reason for the sharply degraded performance. Is
> there something about Windows 7 that degrades the performance of NTP? Or is
> there anything subtle I can check?

NTP list - setup at http://lists.ntp.org/listinfo/questions
- might be better. Search archives for relevant topics.

Power saving is more ubiquitous with Win 7 and it defaults
to Balanced, with high jitter, and system changes make it a
less consistent timekeeper than XP - Windows 8 is better.

Ensure your BIOS is set to as much as possible disable spread
spectrum (reduces RFI) and sleep states (reduces power).

Go to Control Panel/Power, ensure your Power profile is set to
High Performance and Put the computer to sleep is set to Never,
then go into Advanced settings and set more things to
Maximum Performance, Never, Disabled, or 100% as appropriate.

Take care. Thanks, Brian Inglis

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