BIOS won't stay set

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BIOS won't stay set

Postby ~PJ~ » Thu Jan 19, 2006 2:15 am

Q. What do I do when my BIOS / time / date settings keep changing?
A. Change the CMOS battery
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Postby ajrox » Thu Jan 19, 2006 5:19 am

you might also see a "CMOS configuration" or "CMOS mismatch" durring boot up. as stated above, try replacing the CMOS battery. they are cheap. and no, a watch battery wont work. needs to be from the computer shop so you get the right one.
good luck
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Postby ~PJ~ » Thu Jan 19, 2006 6:51 am

Ideally take the old battery with you if you're not sure. There are several of the same size and similar spec, but they are NOT interchangeable.

CMOS checksum error is the other possible code.
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Postby cw4cam » Thu Jan 19, 2006 6:56 am

Double click on the "time" on the tool bar. Dialog box comes up. click the tab "internet time" if the box "sync to internet time" is checked, un check, reset time, see if that fixes it.
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Postby Karlsweldt » Sat Jan 21, 2006 8:27 am

Commonly known as the "Bios" battery, it is really a battery backup for the EPROM memory in the CMOS, which stores the info on how your system is configured, along with the date and time. The average life of the battery is about 3 or 4 years, after which it should be replaced. The power "curve" of the lithium cell is not sloped gradually.. it suddenly falls off, from almost-full to near-none. Normal alkaline and other cells have a more gradual slope to their voltage/current output. Typically the Bios battery is a 3 volt, or 3.6 volt for older models. Although in popular use some years ago, the "Dallas Real Time" chip was a separate clock/date unit, with its own battery sealed inside, plus the clock oscillator. They are becoming rare to find, and are quite expensive. Normally about the size of a domino, on older mobos. Some were soldered directly to the mobo.. others were socketed. Some of those mobos had an external battery connector, to continue using the same chipset if the battery died.
Definitions..
BIOS.. Binary Input/Output System
CMOS-- Complimentary Metal Oxide Semiconductor
EPROM.. Erasable, Programmable read-only memory.
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