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Clock not updating

edmelo
edmelo asked
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Last Modified: 2011-04-14
I have recently been having a problem with the clock in the PC not updating properly while the computer is turned off.  Assuming it was a battery problem I replaced it.  One thing I noticed while doing this leads to the following questions:

I assumed that when I pulled the battery I loose the CMOS setting.  However, I didn't.  I later read that some PCs now store this info in non-volatile ram.  OK, I'll buy that.  However, the date remained correct as well even though the battery was out for several hours.  

Is it the case that the date is also stored in non-volatile ram and it's only the actual clock that uses the battery power when the PC is turned off?  Just curious.  
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Commented:
some mother boards also have a capacitor that stores a charge that allows the CMOS and clock to keep their settings for some time after the battery is disconnected. I am a bit surprised that the settings were retained "for several hours" , but considering the tiny amount of current required to keep the settings it seems (and I guess IS) possible. I've never left a battery disconnected for that long.

Commented:
Is this PC connect to the network?, if that is the case please check your file server, the time may be set back by your server.

Author

Commented:
No, it's a standalone PC.

Commented:
The only thing I can think of if the CMOS battery wasn't the problem, is bad MB (the connection from the battery to the BIOS bad).  What MB do you have?  I agree it is interesting that CMOS saved its setting for a number of hours with no battery, a few minutes, yes, but hours?  You might the website of that manufacturer, it is possible there is a flash chip on the board.  Also, try to reset the CMOS jumper to clear, then back to the default, see if that changes anything.

Good luck,
Jon

Author

Commented:
Well, everything is working fine since I replaced the battery so either the original battery was bad even though I measured almost 3v on it or the contacts were loose (I pinched them together before inserting the new one.  Still rather confused by what I had found though.
Commented:
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Author

Commented:
That's probably the answer.  It's still working ok.
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