Allen Bradley Industrial PC clock time changing byself

Hi;

At one our machine, there is an Allen Bradley Industrial PC having windows XP. This PC has many other programs to communicate with other systems of machine.

We have been facing an issue that PC clock time changes byself. We have checked that auto update date and time and time synchronising is off. We have disconnected the PC from machine and closed other programs but still clock time changes. We have also replaced the mother board cell. If we set the time, after 15min to hours, time is changed byself.

Do you please help how to fix the issue?

Can you provide more information on the system? What software is running on the PC? What other devices are connected to it? When the time changes, is it changing to the same time each time? Or is it an offset of the current time?

Windows 10 is the latest and what is your NTP server? (Don't use windows XP at least upgrade to windows 7 which is now obsolete.)

Does the time change to the same time every time, or does it appear random?
Could be failing RTC/battery.

What do you mean by 'Allen Bradley Industrial PC?'

Is PC connected to internet? Maybe disconnect internet if possible and see if time changes. Then you will know if offline application causing time change or some online program is making the changes.