Why is the the built-in clock inaccurate?

Even after setting the built-in clock with the correct time, it will delay gradually.

This is because the time-of-day clock in a computer is not as accurate as compared to a wrist watch.
The running of softwares may also affect the accuracy and thus making the clock less accurate.
As it is difficult to maintain accuracy of the time-of-day clock in a computer due to these reasons, setting the clock with the right time often is required.

A. There is a substantial time difference
If the clock advances or delays by more than few minutes a day even though the computer has not been placed in a extremely hot or cold place and not left idle for a long time, the software clock may be affected by some kinds of software.
If there is a program that causes delays in response frequently or does not respond, or a utility program that causes the computer operation to be unstable, stop or uninstall it.

B. The clock shows a slower time when it is purchased
The clock may be delayed during the shipment of the computer. This is due to the built-in battery becoming weak. At the time of shipment, all batteries in computers have the same capacity. The length of time between the shipment from the factory and the arrival to customers may differs due to different distribution.
If the clock is behind the actual time at the time of the shipment from the factory, set it correctly. If the clock delays again, please bring the VAIO computer to the local Service Center for inspection.

Please use the BIOS setup program to check the accuracy of the built-in clock:
1. Start the computer and press F2 after the Sony logo appears.
2. Select Date/Time and set correct the date/time.
3. Leave the BIOS setup program running for several hours and check the time of the clock again.