CMOS Battery

[Warped Factor]

My PC's clock is losing around an hour over night when it is switched off which I think suggests the CMOS battery may be on the way out.

Assuming it can be replaced, do you lose all the CMOS/BIOS settings in the process or is there something that retains a small amount of charge to give you time to swap old battery for new as happens with some radios and the like?

TIA.

WF.

[Tinstaafl]

Usually all settings lost, however occasionally there can be some capacitance in the circuits that holds enough charge for the short time it takes to swap batteries.

[Mac the Knife]

You can use CMOSGET and CMOSPUT to save a copy of your settings.

Instructions and link to downloads at http://www.greggore.com/dln091802.htm

Haven't used it for years, but if it worked then it should work now.

[Or you can use Roedy Green's CMOSSAVE from http://www.filelibrary.com/Contents/DOS/54/18.html ]

[fobotcso]

...then, of course, you could change the battery while the PC is running; if you can get at it.

Or, remember paper and pencil? It's not a big deal to write down the few changes you will have made from the defaults. Then, if you have to, re-enter them after the battery change.

[Naples Air Center, Inc.]

Warped Factor,

The internal clocks on motherboards are extremely cheap. They are not known for keeping accurate time. (One of the chief reasons Microsoft added Internet Atomic Clock Time Checking feature into WinXP.)

If your mobo loses time while you have the computer turned off but plugged into the wall, it is not the battery. The motherboard battery is only used when the computer is off and not plugged into the wall. (or when the Power Supply is switched off by the switch on the back, if it has one.)

Take Care,

Richard

[Ausatco]

Richard,

If he has an old computer, like the one I just gave away, it has no software off function, or "partial off" function, just a big mother rocker or push button switch on the front. "Off" is "Off" - no juice getting to the power supply or mobo, even if still plugged in at the wall, so when it's off it needs its CMOS battery.

I'm glad I've moved on ...

AA

[Warped Factor]

Hello Folks,

Many thanks for the replies.

PC is 12 months old, runs WinXP Home and does have an on/off rocker switch on the back as well as the on/off button on the front.

It also seems to have started behaving itself again and over the two days since I posted the message at the top of the thread has not lost any time at all despite being off from the mains for a fair chunk of that time.

So, I think I'll leave the CMOS battery alone for the time being I think and just see if it happens again in the future.

Thanks again.

WF.

p.s. Richard, was out at NAC earlier this year and will be with you again mid Jan with some friends :D

[Naples Air Center, Inc.]

Warped Factor,

Glad to hear you scared your computer into behaving itself again. :ok:

I was thinking about possible causes. One thing that is known to affect the clock is Antivirus programs, another is actual viruses. (Just thinking that you set the clock when you start the computer, but do not notice the time on the screen when you shut down. No one looks at it on shutdown.) It could be the time slows down while operating the computer and then when you shut down it is already off by an hour or so.

If you just want to do a scan of your computer to check for Viruses, run:

Trend Micro's Housecall (http://housecall.trendmicro.com)

The power button the front of your computer should be a push button which is a "Soft Off" and the rocker switch on the back of your power supply is the actual power shutoff for the computer.

Take Care,

Richard

P.S. Looks forward to seeing you in January.

[Warped Factor]

Thanks for the further info and suggestions.

I'm 99.9% certain there are no viruses (virii?) involved. I'm running NAV2003 with up to date definitions and regular scans with nothing nasty being revealed.

I also used the clock sync utility to reset the time on the occasions it was out on booting up. Must admit I thought it checked the time a bit more regularly than just once a week though.

Over the last few days it seems to have been behaving itself again with the time being correct on booting up, so I think for the time being I'll just keep a wary eye on it. Hopefully it was just "one of those things" :)

Thanks again.

WF.