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Cmos error

G

gerrydoire

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Aug 25, 2008
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This isnt vintage, but so many people on here seem know alot more about computers than I do...

I have a Pentium 4 Computer, it currently has a 3ghz chip in it.

The thing won't keep bios settings, tried new batteries, tried resetting it, nothing works.

The computer works fine, no errors, all hardware is detected it seems to work fine..

Now here is the odd thing, long as I leave the power plugged in, even with the computer turned off, the cmos keeps its setting, but once i pull the power cord, the settings are lost instantly.

Anyone ever encounter this and have any suggestions?
 
PCI bus conflict

PCI bus conflict

I've seen this kind of thing on occasion on some boards if there's a bus/resource conflict. I'm assuming the hard drive controller is on the motherboard. Can you pull all cards except the video card, and see if it makes a difference ? Oh, and if you've got it overclocked, turn it off.
patscc
 
there's also sometimes a jumper on the motherboard itself that is used to clear CMOS. the jumper itself is often times red in color and located near the battery itself.

If you got this computer from someone else at some point, maybe they moved the jumper?

leaving the machine plugged in makes sense with this condition. all ATX based machines now are somewhat "on" whenever the box is plugged into the wall.
 
patscc said:
I've seen this kind of thing on occasion on some boards if there's a bus/resource conflict. I'm assuming the hard drive controller is on the motherboard. Can you pull all cards except the video card, and see if it makes a difference ? Oh, and if you've got it overclocked, turn it off.
patscc
Click to expand...

The only card in it is the video, all the rest is built in..
 
hargle said:
there's also sometimes a jumper on the motherboard itself that is used to clear CMOS. the jumper itself is often times red in color and located near the battery itself.

If you got this computer from someone else at some point, maybe they moved the jumper?

leaving the machine plugged in makes sense with this condition. all ATX based machines now are somewhat "on" whenever the box is plugged into the wall.
Click to expand...

Yup, when the thing is powered down, the nic connector still flashes, so its still getting some juice to the mb, but what gets me, what drives me nuts, the problem could be something simple like a bad resistor worth nothing....
 
Is there any programs that I could run that can scan all the onboard chips to see if there is a problem?
 
manual

manual

Can you post the model number of the board ? It's time to look at the manual. I like hargle's suggestion that the CMOS clear jumper is in wrong (it might be black)
They're all sorts of diagnostic utilities out there, but let's try simple stuff first.
Does it have a flash BIOS ?
patscc
 
patscc said:
Can you post the model number of the board ? It's time to look at the manual. I like hargle's suggestion that the CMOS clear jumper is in wrong (it might be black)
They're all sorts of diagnostic utilities out there, but let's try simple stuff first.
Does it have a flash BIOS ?
patscc
Click to expand...

I downloaded the latest flash and the chip took it, so one would assume the chip isnt damaged?

The motherboard is a DFI PT880-AL sometimes called an ALF
 
flash

flash

No. The fact that the chip took it really just means it fit.
It's up to the utility to determine if the motherboard it's flashing and the new BIOS code are compatible.
Did it have this problem before you flashed it ?
patscc
 
patscc said:
No. The fact that the chip took it really just means it fit.
It's up to the utility to determine if the motherboard it's flashing and the new BIOS code are compatible.
Did it have this problem before you flashed it ?
patscc
Click to expand...

I got no errors when I flashed it.
 
Interesting tidbit, the battery on a modern system ONLY powers the clock. Modern computers don't use a CMOS anymore, but NVRAM instead, which obviously doesn't use a battery, it's nonvolatile..
 
evildragon said:
Interesting tidbit, the battery on a modern system ONLY powers the clock. Modern computers don't use a CMOS anymore
Click to expand...

Not true! Modern motherboards still use CMOS to store BIOS and setup data. Both my AM2 and AM2+/AM3 motherboards use CMOS as well as other boards I still use.
 
flash

flash

evildragon said...but NVRAM instead
Click to expand...
Technically, NVRAM is non-volatile RAM, typically battery-backed, often with an internal battery, like Mostek's MK48T02, which Sun owner's have come to hate, or the RAM portion of the Dallas Semi clock chips, that the rest of us have come to loathe.
Did you mean FLASH ?
patscc
 
evildragon said:
Interesting tidbit, the battery on a modern system ONLY powers the clock. Modern computers don't use a CMOS anymore, but NVRAM instead, which obviously doesn't use a battery, it's nonvolatile..
Click to expand...

I think the worst part of modern motherboards or anything modern, no one will even try to fix them....

Made in china, throw it away, buy another, so much waste, especially when the fix could be something simple.
 
i had a similar problem once with a box built for my son. turned out the battery holder was not holding the battery securely. sometimes when the box was moved it forgot the settings. nearly drove me sane trying to figure that one out. maybe a loose connection? or similar.
 
Just because the BIOS setup utility says "CMOS" doesn't make it so. It's there for legacy reasons. All my modern motherboards post say "Checking NVRAM".

The term remains in wide use but it has grown into a misnomer: non-volatile storage in contemporary computers is often in EEPROM or flash memory (like the BIOS code itself); the remaining usage for the battery is then to keep the real-time clock going. The NVRAM has a typical capacity of 512 Bytes, which is enough for all BIOS-settings.
Click to expand...

http://en.wikipedia.org/wiki/Nonvolatile_BIOS_memory

Besides, I've tried it on my Mac Pro, MSI P4, and IBM ThinkCentre P4. Took the battery out for an hour, and the only thing lost was clock. BIOS settings remained.
 
Last edited:
Vlad said:
Not true! Modern motherboards still use CMOS to store BIOS and setup data. Both my AM2 and AM2+/AM3 motherboards use CMOS as well as other boards I still use.
Click to expand...

One wonders why NVRAM wasn't used on the first 5170 to store configuration information. You can find the Xicor X2444 256-bit serial NVRAM on lots of old ISA cards (e.g. the Intel Aboveboard and lots of NICs). The chip predates the 5170 and requires no power to maintain its settings.
 
evildragon said:
Just because the BIOS setup utility says "CMOS" doesn't make it so. It's there for legacy reasons. All my modern motherboards post say "Checking NVRAM".



http://en.wikipedia.org/wiki/Nonvolatile_BIOS_memory

Besides, I've tried it on my Mac Pro, MSI P4, and IBM ThinkCentre P4. Took the battery out for an hour, and the only thing lost was clock. BIOS settings remained.
Click to expand...

Interesting. There's a big discussion on that very statement in the discussion page on wikipedia. I personally don't believe it, although I haven't been doing PC BIOSes now for a half dozen years, so things may have changed. Back in my day, Phoenix most certainly (early P4 motherboards anyway) had BIOS settings stored in a CMOS device, accessed through IO port 70h/71h which could be nuked by removing the battery or just writing an invalid byte to those IO ports to blast the checksum. Read/writing flash is a whole different ballgame, and requires significantly more code and access to high memory to do it.
 
variations

variations

Perhaps the sensible answer is to just say all motherbaords are not the same, and manufacturers adopt different technologies at the same time.
Look how long it's taking for them to adopt fail-safe flash BIOS's.
patscc
 
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