David J Taylor wrote: > Is: > > Performance Counter Frequency: 3.580 > > a guarantee that the TSC isn't being used?
AFAIK if the TSC is used then the clock frequency reported for QPC matches the CPU's clock full clock frequency, and IIRC then according to some MS docs the reported frequency does not even change when the CPU's clock is decreased for power saving. IMO that also wouldn't make much sense. >From what I've seen the reported QPC clock frequency depends on which timer circuit is being used. Some months ago I've already posted what I had found: http://lists.ntp.org/pipermail/questions/2009-March/022159.html But of course I can not *guarantee* this is always correct ;-) In that article there are also some hints which Windows versions / service packs use which timer to implement QPC. I've just reread that article and found this perfectly matches what Alan has observed, i.e. Windows XP SP3 should use the PM timer even if no /usepmtimer flag has been added in Windows' boot.ini. Of course it does not explain the problems Alan is observing. Regards, Martin -- Martin Burnicki Meinberg Funkuhren Bad Pyrmont Germany _______________________________________________ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions