The system time becomes completely wrong whenever the PC wakes up from sleep

A failing CMOS battery is a likely cause when the clock is wrong after sleep or shutdown, especially if this happens across affected machines and the time appears to drift back to hardware clock values. One documented symptom is that Windows time can revert to the CMOS clock setting, and Microsoft Q&A guidance also notes that if a computer loses time after shutdown, that indicates a faulty CMOS battery.

A Windows Time resync problem is also plausible. One accepted troubleshooting path is to verify that the SynchronizeTime scheduled task is enabled in Task Scheduler under Task Scheduler Library > Microsoft > Windows > Time Synchronization, and that the Windows Time service is running in services.msc. If needed, change the Internet time server and test synchronization again.

There is also evidence that sleep and hibernation transitions can interact with system time. Microsoft documents cases where, after resume, the system time changes and is synchronized with the hardware clock. That means an incorrect hardware clock can surface immediately after wake.

Based on the available information, the most supported interpretation is:

1. Check the hardware clock / CMOS battery first if the time is grossly wrong after wake or after power-off.
2. Verify Windows time sync components next:
   • Task Scheduler > Microsoft > Windows > Time Synchronization > ensure SynchronizeTime is enabled.
   • Services > ensure Windows Time is started or restarted.
   • In Control Panel > Date and Time > Internet Time, confirm the correct time zone and test another time server.
3. If the issue persists across multiple client machines, that points less to a single bad battery and more to a common platform, firmware, or configuration factor. The provided context does not confirm ACPI/chipset driver faults as the cause, but it does show that wake behavior depends on firmware, RTC, and power-state handling.

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