A small setting behind a lot of odd problems
When your system clock drifts, you can run into unexpected issues like online banking errors, security certificate warnings, or failed logins. Keeping automatic sync turned on helps prevent all of this.
If your computer won't turn on at all
A clock that keeps resetting itself is sometimes an early sign of a dying internal battery, which is also a common cause of other startup issues -- worth checking if your computer has trouble powering on too.
Frequently Asked Questions
The time keeps drifting even with automatic sync on.
If your motherboard's backup battery (the CMOS battery) is old and drained, the clock can keep resetting itself, and you may need to replace that battery.
Does syncing still work without an internet connection?
No -- your device needs to reach an internet time server to sync, so automatic syncing won't happen while you're offline.