* A computer actually maintains three separate clocks:
The Real Time Clock (RTC): located on the system board (motherboard) and powered by the CMOS battery so it is consistently updated even if the system is not receiving AC power.
The CMOS Clock: a logical clock stored in the BIOS chip on the system board. Its settings are maintained (but not updated) in non-volatile RAM while the system is powered off.
The Operating System (OS) Clock: a logical clock stored in system memory and is cleared each time the system is powered off or rebooted.
* When a computer is powered on, the CMOS clock synchronizes with the RTC during the POST (Power On Self Test) operation. When the operating system boots, it reads the current time from the CMOS clock and maintains its own, essentially independent, OS clock. The OS clock does not synchronize again with the CMOS clock unless the OS clock is manually changed (at which time both the CMOS clock and RTC are set to the time stored in the OS clock), or the system is rebooted. Therefore, the OS clock may hold an incorrect time if running tasks slow down the operating system scheduler, while the CMOS clock and RTC continue to maintain the correct time
* Click Start-Shutdown-Shutdown-Ok or Click Start-Turn Off Computer-Turn Off
* 99% of the time, your time loss problem goes away when the system is taken OFF of the network. Disconnect the system from the network cable. Power it back on. Wait 30 minutes. Does it lose time?
* Restart the computer. At the blue Dell screen, rapidly tap the F8 key (do not hold it down)
* At some point, the Advanced Options menu will appear
* Scroll to and select Safe Mode [press Enter]
* Windows will start in Safe Mode. Close any boxes that may open, just get to the desktop. Let the system run for a while and check the clock down in the Windows system tray. Does it lose time? List the results.
Why does my computer lose time or not properly update its clock, and how do I correct this problem? <ADMIN NOTE: Broken link has been removed from this post by Dell>
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