System Clock slows despite changing CMOS battery

[Guest]

While replacing CMOS battery is the most obvious solution to solve the slowing PC clock, it did not help in my case.

The PC clock slows down after I power it down and restart after a few hours. The gap is small, about 5 - 7 minutes behind.

I have not yet tested it by keeping it off for days if the gap further increases.
I have already replaced CMOS battery but issue persists.

The strange part is that the clock otherwise seems normal when PC is running . The issue comes only after switching it off and then on after a few hours.

Also just note that Windows time sync feature is irrelevant here as the issue is at BIOS itself. Before booting into Windows I purposely boot to BIOS and check the clock, to find it behind by 5 - 7 minutes.

I am really curious to know what might be going wrong in this case. Thanks.

 

[boju]

Windows does modify bios's time. Way i see it the bios wouldn't know real time until after Windows is loaded. So with pc off, time could change depending how quick/slow the timer is.

Does sync feature not work still?

 

[boju]

https://www.wilderssecurity.com/threads/does-bios-time-get-updated-accordingly-with-os-time-update.313255/

http://www.tomshardware.com/forum/71869-63-does-changing-windows-time-change-bios-time

 

[smorizio]

can be bad bios or clock chip. try reflashing the bios and then clear the cmos. if the error still there if the mb still under warranty rma it.