I'm working on a case where the time accuracy is important. I have worked out the time of a system is 1 minute 30 seconds slower than the UK Time servers. The event logs show regular and normal updates have been performed on the system when connected to the internet, and the system connects daily, on average.
What reasons would cause a bios system time to be 1.3 minutes slower than the actual time server which updates it?
Any help would be useful.
Perhaps CMOS time only gets updated on system reboot? When was the system you are looking at last booted?
I need to explain what would cause a 1 minute delay, there is the manual option done by the user, after a time update. I cannot think of any other reaslistic reason?
CMOS does not need to be rebooted for an update. Its scheduled and instant.
Is the delay 1 1/2 minutes, or 1.3?
one minute 3 seconds
Do you mean slower, or begin. In other words, does the time lag increase with time, or is it constant?
Sorry haven’t explained myself very well. A time recording was taken from the BIOS of the computer. It showed the BIOS at that time was 1 minute 46 seconds faster than a radio watch. This machine has not been connected to the internet since it was first taken. (aprox 3-4 months).
Until this computer was taken, it was connected to the internet daily.
I'm not sure how I can explain why, the computer BIOS time is faster than what it should be. Time is important in this case. The time server on the system uses the same server, as the radio watch.
Is this Windows? What version? There was a bug introduced in XP and, I think, 2003 where the W32time.dll failed to update the CMOS clock. There was a fix to this, but depending upon which Service Pack and hotfix had been applied, you may have run into a situation where patching the system introduced the anomaly.
Can you do a Belarc Advisor report on the system (assuming Windows), to see what versions of the dlls are installed?
seanmcl is (I think) referring to
If the CMOS battery has not been charged for 3-4 months, then the clock is going to wander off internet time. Another approach of OS time accuaracy may be to look at such things as email headers whcih contain mail server time stamps and comparing those to associated MAC times?