How vital is the CMOS battery?

[Will Hay]

Gonna' sound dumb but I've asked daft questions before so I ain't gonna' stop now

How vital is the CMOS battery?

What would be the effect on a computer if the battery needed replacing, ie. it constantly reported the wrong time (on th windows clock) no matter how many times you changed it (the time, not the battery)?
Thanks,
Will

[holistic]

Very Vital
The "CMOS" battery keeps EPROM (i believe) from loosing important imformation such as :

as you said - date
FSB , voltage settings
Harddrive Settings - ie: cylinders , heads, LZ
memory timings and so on ....
You can run without one but you will need to reinput all the necessary data before the machine will finish it's POST (power on self test)

I suggest you hit DEL (or whatever you board needs) and write down all the settings on the screens before you replace the battery.

][

edit : FYI - I have run a 486 with a dead battery before. But as I said ,I needed to reinput info into the BIOS every time I shut it off.

[holistic]

Some helpful reading :

http://www.computerhope.com/help/cmos.htm#01


][

[gmatov]

Will,
Boot into the BIOS, you should see everything set to default, just as though you put a new, unsetup board in the machine. Every thing should be at default. Including the boot order.

Hey,the batt is very important, and should be a 2032, and goes about 2.50 here, pound and a half there?
Go buy a new one. I think someone here a while back told you to go get a used one.. Bull. Buy a new one. Simple little disk 1/8 inch thick, 'bout 1 inch diameter. Should get it any drugstore..

George

[Will Hay]

Right, thanks.
So it wouldn't result in a crash without warning?
Still haven't sorted it George, although it isn't as bad as before.
Will

[pbhalerao]

Will,

Once your computer has booted up, it won't crash because the CMOS battery is dead or weak. However, the BIOS settings are lost every time you shut down the computer. As holistic said, it is very vital that you replace the battery immediately. The typical life of this battery is 3 years. Buy a new one.

Regards,

[pyrate83]

I actually read that the typical life for the battery that keeps your date, time, etc. is about 7 years. Especially if you buy a computer from a major manufacturer. Maybe that info. is wrong but it would seem to me that it's possible to last that long due to the type of battery being used.

[Solarjetman]

The typical life of this battery is 3 years.

Really? I would think longer.

But anyway, you really should replace it unless you want to input the data every time you boot. I had an old 486 that was like that. It would lose the settings and would not start without re-inputting them. I only needed to use it for two days, so I just inputed the data instead of tracking down a battery. Got rid of the system a few days later.

However, if for some strange alignment of the planets, the default configuration on the CMOS is the same as the configuaration of your computer, then it is irellavent to replace the battery (with the exception of the time always being wrong). But the odds of that are slim to none.

[pyrate83]

Does everyone ignore me around here??? I just stated that the typical life of the battery is closer to 7 years, not 3 years.

It's cool though, I'm not pissed. 8)

[Craig Tucker]

I used to have an old amstrad PC3086 that used to take AA bateries for the cmos.

[Will Hay]

So I have to write down all the BIOS settings, change the battery and then make sure all the settinsg are correct?
Man!
The battery came with the motherboard (obviously!) I only bought it 11 months ago
Bastards!
Will

[Solarjetman]

The battery came with the motherboard (obviously!) I only bought it 11 months ago

Uh, was it a used motherboard. If not, maybe you should ask for a replacement from the manufacturer. It should not die so early.

[gmatov]

Will,

Somehow something's not right, here.

If your battery IS dead, when you shut down the computer for real, with the PSU switch, you lose all your own settings, those that you input at setup.

It goes to default. If you, for instance, have an onboard Video Chip, and you set it for 64 megs video RAM, it would now have only 16, or whatever default is. Same with your chosen boot order, stuff like that.

If your clock is losing time, but nothing else is wrong, I don't know how it can be the battery. If you have it set to suspend to RAM, STR, or Soft Off, I think the board is always powered, so the clock should not go to 0 on reboot.

Mine, for instance boots when I hit any key, meaning the board has to be powered to sense the key stroke. So, even if the battery is dead, the clock should keep time.

Now on an AT machine, you actually cut the power completely when you clicked off, had to go to default on reboot.

Every thing Holistic mentioned, other than the time and boot order, are auto-detected on bootup, FSB, voltage, CPU, disk parameters, etc.

Have to go to the link he provided, read more about it.

BTW, have you been shutting down entirely, complete power down?

Cheers,

George

[Will Hay]

The battery came with the motherboard (obviously!) I only bought it 11 months ago

Uh, was it a used motherboard. If not, maybe you should ask for a replacement from the manufacturer. It should not die so early.

No, it was a new board.
Will

[Will Hay]

BTW, have you been shutting down entirely, complete power down?

Hey George.
Not sure what you mean.
You member my problem, right?
Completely unprovoked restarts, no warning, nothing.
When I start up I have to change the clock and then within twety minutes perhaps it changes to a completely different time.
Last 48hrs I've been getting a message (which I can't fully remember), something along the lines of...
...."your system clock does not match that of the xxx, go to control panel....applet....xxxxx some bloody thing etc. etc. etc."
Sorry, vague, I know.

What would be the effect of faulty memory?
I'm sorry, but I need to know the cause to be able to justify expense, and I know, that's hard to determine without trying swapping things out.
I made this machine myself end of last year (it's my third custom built, I have a fair (but not comprehensive) grasp of what I'm doing but I'm stumped here
Sure is a pain when it resets during an encode or dvd burn
Will

[gmatov]

Will,

If it tells you to go to control panel, Time and Date, you can get there by double clicking on the time in your system tray, set th time, click Apply an OK.

The next time you get the wrong time, reboot, if you're not in the middle of an encode or burn or some thing, enter setup and see if the system time is correct. If the times don't match, I would rule out the battery, the CMOS batt is working as it should.

I probably shouldn't be advising on this, as, on rare occassion, my own system also reboots, I haven't the foggiest why, never remember what caused it, except possibly having too many windows and tabs open in Netscape. I might have 6 to a dozen open, specially here on the forum, but using too many resources should slow the machine down, not cause a reboot.

This machine has a 400 watt Antec, so I am ruling out rhe power supply.

Do you have a MoBo monitor in Windows? Mine only has the BIOS monitor, and when it does reboot, I try to go to setup to check if the CPU has gotten too hot, but never has.

You might try the same. An encode might get the CPU usage high enough to hit a set temp in BIOS, but I think it should flash a warning. Thing is mine hasn't done it during a capture or encode, so I'm lost.

Cheers,

George

[zodiac]

you might want to go to the bios page of your motherboard and see if anything aplys to you.
restarting could have somthing to do with xp or the video card.
...or it could be just that you have sp1 installed,will :P

[Will Hay]

...or it could be just that you have sp1 installed,will :P

Is this a joke?
Will

[Will Hay]

Hey George, thanks for the post.
One thing that troubles me is...
...the computer doesn't have to be working hard to reset.
Most times it resets just before if finishes loading windows, other times it could be when I'm writing an email and have only a browser window open or it could be during a burn or encode (although this is very unusual, I make sure the machine is stable, use it for an hour or so first) before I start anything like a burn.
What would be the effect of faulty memory?
Will

[Will Hay]

I did have a system monitor installed for a while, oh no, wait, I just kept checking the temp in the BIOS and nothing jumped out at me that I should worry about.
If I remember correctly, at worst it seemed to be around the mid 40's mark.
Will

[flaninacupboard]

Is your RAM all on one stick, or 2X256? if it's 2 256's i'd take one out and check for problems, if none, swap them over and try again.
Although if it's all one sitck, you're stuck.

As suggested check what power settings you have, specifically temperature warnings. my computer will (entirely randomly) report a CPU temp of about 80 degrees for one second, and then drop back to 45. if my machine was set to reboot when it hit 60 (which i think it was when i first bought it) it would reboot at this point.

I can't say this enough, try a different power supply if you have one! if not, they can be had for less than £10 from www.ebuyer.co.uk they're always handy to have round anyway, so go buy one. a lot of intermittent problems seem to be caused by unerpowered/dodgy PSU's.

[flaninacupboard]

This is so important it deserves a whole new post on it's own!!

Did a little digging, assuming the random-reset pc is the one in your profile then according to this website you have the same onboard sensing equipment as me, I've got the K7vmm+.

Grab the bit of software on that site, and set it up, with data logging every second. after a reset, open the log and see if the temp spiked just before the reset.

[RabidDog]

it could be something as simple as a dodgy power lead. It sounds like something is shorting somewhere. Randoms reboots under no load are unusual> return the board if its under warranty.. they do get cracks and such like which may not show up till some time after installation. Has this system ever worked properly?
The battery is ( like) a watch battery and will last as long. 7 years plus. but is it a rechargeable battery that is not being charged?? CMOS

[Will Hay]

Is your RAM all on one stick, or 2X256? if it's 2 256's i'd take one out and check for problems, if none, swap them over and try again.
Although if it's all one sitck, you're stuck.

It is one stick.

I can't say this enough, try a different power supply if you have one! if not, they can be had for less than £10 from www.ebuyer.co.uk they're always handy to have round anyway, so go buy one. a lot of intermittent problems seem to be caused by unerpowered/dodgy PSU's.

I have an Antec 340w PSU so I would imagine this isn't the problem

[Will Hay]

it could be something as simple as a dodgy power lead. It sounds like something is shorting somewhere. Randoms reboots under no load are unusual> return the board if its under warranty.. they do get cracks and such like which may not show up till some time after installation. Has this system ever worked properly?

Yeah, it was great up until about three/four months ago.
Although the very fact that I have constant problems with the time leads me to believe it's the board.
Will

[gmatov]

Will,

Have you gone to the BIOS on reboot to see what the time is set at there?

If your battery was bad, again, unless you unplugged, turned off the switch on the back of your machine, or flipped the switch on your UPS and Surge Protector, I think the board is constantly live.

A shorted wire seems to be out, too. Reason is, I just put together a new system, 2400XP, new board, case, OLD floppy. Turn on, CPU fan spins up for maybe 5 seconds, shuts down. Go to pull stuff out, power to drives, floppy included, burnt myself on the floppy wires. Good thing is the PSU tripped, reset itself.

Innyhoo, if a wire was the culprit, it would be more often. (Hell, it might be doing it every 5 minutes, really don't know.)
Try wiggling all the wires, flexing the board, tipping all your cards back and forth, see if you can make it do it on command.

The RAM is the one thing I don't think it is. With bad RAM, you get a no boot, or an error on boot, or a page fault, whatever. Not a random reboot.

You are running XP, right? My browser is f'd up, can't see your comp details. Have to check MS to see if they have a "random reboot" problem.

Hell's bells, Mine won't even let me load 98, somekind of extended DOS error, formatted, etc, updating BIOS soon as I finish this.

Cheers,

George

[Will Hay]

It did it twice this morning, once during the start of an encode and the other when I was cheking e-mail, and three times last night..
..once when I got home at 5pm-ish and turned it on and it rebooted before finished startup loading, same again at 8pm and then again at about 9pm halfway through writing a long PM to someone here
Grrrrr!
I'll check the BIOS tonight.
Will

[gmatov]

Will,

I might have to eat my words.

I checked MS on my problem and one was possibly bad RAM.

The piece of 512 meg that was perfect in the old 1800 locked the new machine. Pulled it, left in 256, was able to install, so, I'll be damned.

Wouldn't have a 128 laying around, would you. Have to say it's worth a try, after this.

George

I'm on the 3rd machine now, the one for my kid, so I can give hers to my g'daughter. G'son has a 1200, wouldn't be right to give the girl an 1800, so that goes to the daughter.

[Will Hay]

Development:
Reset three times tonight, the latter right in the middle of a massive post in offtopic
Anyway, after restarting I saw a BIOS message which stated (words to the effect of)...
CMOS time wrong
CMOS system memory (maybe, maybe not this exact wording) set incorrectly.
I went into BIOS and time was set to midnight 26 July 2002 (which I think is the copyright date when the machine first starts).
Now, that is a development, right?
Will

[FOO]

You could eliminate one problem immediately
by actually measuring the battery voltage
I had one with a loose battery clip (because of gorillas bending it)
The clock will screw up more than the static settings at low voltage.
So a bad clock definitely suggests battery problem.