Chronograph is a simple application which can sync your PC time with the Atomic time. This application uses the atomic clock servers of the National Institute of Standards and Technology (NIST). Application developer claims the time difference with actual time and your PC will be a maximum of 0.5 Seconds.
Before proceeding just a small thing, you may be aware that you can synchronize your system time with the time.windows.com from the adjust date and time => Internet time tab. This also provides accurate time but it may not be as accurate as Chronograph (we believe the developer).
Features of Chronograph
Manual, periodical and wait-for-connection operating modes.
Program will be updating the time from a server which will be available at that time from a list of servers.
Ease of use. Application works in the background after the initial setup.
This application worth is $19.99, while you can get this application for fre for a limited time (Today only March 30, 2015) from the Giveaway Of The Day website. If you are interested you can check their website
There are Free alternatives for this application you may try Atomic Clock Sync which is free. Compared to the chronograph Atomic Clock Sync will work fine with the 64 bit versions of Windows too. Many users are complaining that Chronograph is not working fine with the 64 bit operating systems.
http://www.worldtimeserver.com/atomic-clock/