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incorrect system time (4 seconds off per minute)
Hi all!
We have two computers here with the same hardware and software (see below for details), and on one of them the internal timing is incorrect by ~6%, which can be observed in many different ways:
- After synchronizing the local clock with an NTP server by the command "net time /set" and waiting for exactly one minute, the local clock has advanced by 64 seconds (after some longer period of time, the clock is automatically synchronized again, so in the long run the local clock is correct, but constantly fluctuating).
- The value reported by GetTickCount() (supposed to be milliseconds since system start) increases by ~64000 per minute.
- The value reported by QueryPerformanceCounter() divided by the timer frequency according to QueryPerformanceFrequency() increases by 64 per minute. This is true both with and without the boot flag "useplatformclock" (i.e., using HPET and the default clock source, respectively).
- The CPU clock frequency according to the registry (HKEY_LOCAL_MACHINE\HARDWARE\DESCRIPTION\System\CentralProcessor\*\~MHz) is 2921MHz (instead of 3100MHz) for all CPU cores.
- The CPU clock frequency reported by the CPU-Z tool (version 1.53.1) is 2921MHz. Interestingly, newer versions of CPU-Z (up to 1.64.0), which are aware of the clock multiplier, report a frequency closer to the correct value, but still not exact.
- The bus speed reported by CPU-Z is 188.48MHz (instead of 200MHz).
- The peak frame rate of an external CameraLink camera connected to a Matrox frame grabber is reported by Matrox' IntelliCam tool as 144Hz (instead of 150Hz).
The CMOS clock is correct as can be observed when watching the clock in the BIOS Setup even before booting the OS. So there seems to be some very fundamental error in the time base from which the system derives many other time-related services, which are all incorrect by the same factor.
Do you have any idea which hardware component and/or system configuration entry is responsible for such behavior, and how it can be fixed?
Thanks & kind regards,
Markus
P.S.: Here are some system details:
- Microsoft Windows 7 Ultimate 64-bit SP1
- mainboard Supermicro H8DCL
- dual AMD Opteron Processor 4234 3.1GHz
- BIOS American Megatrends Inc., Version 2.0 (12/8/2011)
I think these are the relevant components, if you need more info for diagnosis, please let me know!
Last edited by grabner; 24 May 2013 at 09:10. Reason: fixed typos