Cmos battery not backing up bios setting

Tried two different batteries (a cr 2026... I think? And 2032) and plus side facing both down and up. It forgets whenever the power is unplugged. The terminals don't seem to be broken, I have no idea what's going on. It's a p3-700, surprisingly I have a p166 here which has never needed a new battery at all.

I'd start by digging out the manual for your board and looking at all the specifics about what batteries you can use, and if there are interesting jumper configurations that are affecting it (like if you have them in a configuration that resets the settings every time).

Aliotroph? said:

I'd start by digging out the manual for your board and looking at all the specifics about what batteries you can use, and if there are interesting jumper configurations that are affecting it (like if you have them in a configuration that resets the settings every time).

Would it be acting this way if the clear cmos jumper was set to on?

invictius said:

Would it be acting this way if the clear cmos jumper was set to on?

Yep, that would prevent settings from being saved and maybe shorten the battery lifespan.

Batteries usually go plus sign up.

GreyGhost said:

Yep, that would prevent settings from being saved and maybe shorten the battery lifespan.

Batteries usually go plus sign up.

Nothing on the board like a model number, what's a lightweight utility that will let me do that?

What OS are you running on it? CPUID for windows might tell you useful things, if you're able to run it. On a Linux-based OS, dmidecode.

My overwhelming suspicion is that you are not inserting the battery correctly and that the contacts are not connecting with the battery socket. If it were an OS issue, you'd see angry flashing error windows when you booted. What made you think it was OK to take it out? They last for years. Taking out a CMOS is a 101 for messing with stolen computers. Look at a video on how to correctly insert the battery or take it to a professional.

invictius said:

Nothing on the board like a model number, what's a lightweight utility that will let me do that?

Make a note of the BIOS string ID that's displayed during startup and try the tools on this webpage.

deadwolves said:

My overwhelming suspicion is that you are not inserting the battery correctly and that the contacts are not connecting with the battery socket. If it were an OS issue, you'd see angry flashing error windows when you booted. What made you think it was OK to take it out? They last for years. Taking out a CMOS is a 101 for messing with stolen computers. Look at a video on how to correctly insert the battery or take it to a professional.

I hadn't turned it on for about 7 years, got the cmos error so obviously suspected the battery. Put in the same kind of battery I took out, no luck. Changed polarity, no luck. Took it to someone who said the wrong type of battery was in there, got the proper one, no luck putting it in both sides. I put it in the same way he did, pull the tab on the side that's holding it in, put the new one in until you hear that tab click in place.

deadwolves said:

What made you think it was OK to take it out? They last for years. Taking out a CMOS is a 101 for messing with stolen computers.

What? Curiosity alone is sufficient reason to take it out. Completely harmless. His reasoning sounded good enough anyway. Those things do die sometimes.

Regarding the mobo model: some PCs will display it in the BIOS. I honestly can't remember how common that was in the 90s. I take it this machine is a generic beige box because something built by a big company would be very easy to Google.

On PCs/laptops older than 10 years, I'd say I encounter a bad button battery over 50-60% of the time. Are you replacing an old battery with another old battery? If so it might be a while before you find one that still works.

The irony is that just the other week I restored a pentium 3 machine, had a bad battery, so I cannibalized one from a 20 year old machine which worked (but probably will die of some unknown mold spore or mouse poop disease as a result of touching it).

deadwolves said:

They last for years.

It's from a P3-700 system. People who were born when it was new can probably drive by now.

In related news, the CR2032 in my P-MMX-233 from 1997 finally needed replacing last month. It's probably been near death for like a year, but I'm lazy so re-entering the BIOS settings was easier than opening the case on the two or three occasions it was powered up.

In other related news, I have a bunch of systems and other electronics that have batteries that could potentially leak. I really should open those up and make sure the boards aren't melting...

GreyGhost said:

Yep, that would prevent settings from being saved and maybe shorten the battery lifespan.

Batteries usually go plus sign up.

Would it still be the clear cmos jumper if it's booting fine while plugged into the power point?

Could be. That jumper won't necessarily prevent the motherboard from booting, just force it to do so from factory default settings and rediscover other system components each and every time.

I checked a few old manuals for the appropriate jumper settings. If it's a three pin jumper, check that the jumper cap is on pins 1 & 2 (the "Normal" position), with a two pin jumper the cap should be sitting on one pin only, or removed. Power down the computer before making any jumper changes.

deadwolves said:

My overwhelming suspicion is that you are not inserting the battery correctly and that the contacts are not connecting with the battery socket. If it were an OS issue, you'd see angry flashing error windows when you booted. What made you think it was OK to take it out? They last for years. Taking out a CMOS is a 101 for messing with stolen computers. Look at a video on how to correctly insert the battery or take it to a professional.

Or he just misconfigured ram timings, perhaps?

101 for messing with stolen computers? WHAT DOES THAT MEAN, MAN!

Flesh420 said:

Or he just misconfigured ram timings, perhaps?

101 for messing with stolen computers? WHAT DOES THAT MEAN, MAN!

I don't think ram timings were even a thing in the pentium 3 era.

My old VB9 motherboard would allow the CAS latency to be tweaked and clock speed to be bumped up/down, but that was it.

Flesh420 said:

101 for messing with stolen computers? WHAT DOES THAT MEAN, MAN!

Clearing whatever password was set in the BIOS.