Have you heard of Atomic Clocks? or NIST?

Here is how you can accurately set your computer clock.

In the past you may have been using a separate third party utility to synchronize your computer clock with the outside world. If you’re using Windows XP, this is no longer necessary.
Thanks to the National Institute of Standards and Technology, it has become much easier to do that through the Internet.

1. Just click on the time in the taskbar and go to the INTERNET TIME tab.
   
2. Select the time.nist.gov and click update now.
   
3. You’re all set!.

But hey, this is the computer era and who has time for this manual work?

Here’s how you automate this.

1. OPEN registry editor.
2. Navigate to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NtpClient
3. Double click the valuename: SpecialPollInterval.
4. Set a decimal number (unit is seconds) to the frequency with which you want to have the automatic synchronization carried out.

By default you only see two time servers in the drop down list. A list of many other time servers is available at http://www.eecis.udel.edu/~mills/ntp/servers.html.

To add any other time servers, get the details about the server, start Registry Editor and navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\DateTime\Servers and just add them to the list as:
 

Name:	<next number in the sequence>
Type:	REG_SZ (String value)
Value:	<DNS name or IP address of the time server>