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question about CMOS 1

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Chrispr

Technical User
May 24, 2004
48
CA
I just put a computer together and I am having a few problems on bootup. First off, the PSU wouldn't work with the MB, I tried another PSU and the MB worked fine. Went back to the original PSU, and it magically worked again. So I installed windows after a few tries, weird things were happening on bootup, the primary bootup is IDE-0 and it just went to a black screen and didn't give any message like no OS found.
Now everytime I turn the computer on it says CMOS memory low and it says that the CMOS settings are wrong. I did reset the settings once, but now it won't keep the settings. I have to push f2 which is load default settings and continue with setup. Is this a bad PSU that is not keeping the CMOS settings and giving me the error 'CMOS memory low'?
 
Change your CMOS battery.



Just my $.02

"In order to start solving a problem, one must first identify it's owner." --Me
--Greg
 
Allow me to give a bit more info. Running ECS K75SA with 1000 Mhz processor, 256 PC2700 DDR 266, 40 Gb Hd, windows XP Pro. Bios probably hasn't been updated in a year or two, the MB was gathering dust. Now when I boot it said two things:
"CMOS setting incorrect (or wrong)" and "CMOS Memory wrong" and so I went into the BIOS and selected load optimal configurations and it boots to the screen that lets you choose safe mode or start windows normally. I choose start windows normally and the computer freezes, same with the other settings. The only way I can boot windows is to clear the CMOS memory, get the error messages "CMOS memory low" and "CMOS settings wrong", then click f2 to load normal settings then windows will boot, and I have to keep doing this every time I turn the computer on. If I touch anything in the BIOS it will either load to a black screen or it will freeze in the windows screen with safe mode.

Do you think this has something to do with the CMOS battery or is it something else? Also, never changed a CMOS battery so can you tell me how please.
 
I would definatly say it was a cmos battery problem.

To change you basically open you box, somewhere on your motherboard you should see a thin circle battery. You should be able to get a replacement any any PC/Electrical shop.


Greg Palmer
Free Software for Adminstrators
 
The more I think about it the more it makes sense that it should be the battery so that will be the first thing I try.
 
While your PC is switched on the CMOS is powered by your Power Supply. Meaning that with normal pc usage you can expect at least 5 years out of modern CMOS batteries.

However if your PC is always off (or in your case just a M/B on the shelf, then the battery is in full time usage and would only last approx 1 year.

Greg Palmer
Free Software for Adminstrators
 
Didn't I say this?


Just my $.02

"In order to start solving a problem, one must first identify it's owner." --Me
--Greg
 
Yes you were right the first time. Just needed some time for that to register with me. I forgot that if you have the jumper on say, pin 1 and 2 to clear the CMOS memory, the mother board won't even power up, it has to be on 2 and 3 for it to start. The thing with the low battery supply and the MB not starting up the first time but starting a second time just took some time to register in the back of my head.
 
I think I did it this time. After taking out the battery for the CMOS I noticed my computer booted up twice with no battery. Then after that it would come on, the CPU fan would spin, but the red 'activity' light would stay red and the power light would be green. Nothing would be display on the monitor, it was like it wasn't getting power. My CD-ROM was also making a weird chirping noise like it was spin a CD but there was nothing inside. No activity from HDD. So I figured it just needed a new battery for the CMOS so I got one. Put it in and the same thing happened, no activity from the monitor or anything. I disconnected the HDD, floppy, and CDROM to see if I could at least get into bios. Nothing. Cannot bring power to the monitor, the only thing that turns on is the CPU fan and the activity light immediately just turns red and then nothing happens. Tried reseting CMOS memory and nothing happens. Me thinks I have screwed something up but I just don't know how. I did nothing to my knowledge to fry the CPU and/or MB. I'm pretty sure there is nothing I can do to get out of this one though. Any thoughts?
 
Try the following, make sure you have discharged any static before by touching the case chassis.

Remove the Processor, then reseat. Ensuring that it is correctly inserted and firmly pushed down while lowering the securing arm.

Remove every thing else from the mother board apart from your graphics card if it is seperate from the m/b.

Only plug in your Keyboard and Monitor.

Now switch on and see what you get. If nothing then try reseating the processor again.

If it works then try reattaching items one at a time. Ensuring the cables are the correct way round.

Greg Palmer
Free Software for Adminstrators
 
If gpalmer711 tips fail, then try installing the cpu, ram, etc to other PC and if they work there then the mobo is gone. I know you never did anything but the signs are there, parts are beginning to fail.

Welcome to the world of PC hardware problem, you haven't encounter a burning smell you see:).
 
It's been known to happen that the CMOS data gets messed up and the computer will not boot. Once I even had a PC where the power supply would not switch on (control via the MB). Solution was to remove the CMOS battery and short the terminals for about 20 seconds to absolutely clear the bad CMOS data. Make sure you have the AC power unplugged when you do this.
 
Thanks for the tips guys. I decided to try another PSU just to see what would happen, so hooked up only MB with RAM and video card for the monitor and it worked. Then I thought it might be the PSU, so I hooked up everything to the old PSU and of course it would work again. What would cause that to happen, to go from completely nothing on bootup to everything is working with the same PSU. I'm typing on the computer right now so I don't think I fried anything yet. I wonder if there is still some corrupt CMOS data that is causing that. I did replace the battery and when I boot up I am still getting "CMOS battery low" error message even though its a new batery. Can you explain how one would go about shorting the CMOS terminals btw. Thanks.
 
I would not recommend "Shorting" the terminals, this basically involves creating a connection between the positive an negitive terminals where the battery is. This can be done with any conductive material such a screwdriver, nail, pin etc..

The jumpers that you use to clear the CMOS do pretty much the same thing, just less chance of static discharge.

It wouldn't hurt to clear the CMOS data again, Disconnect the power supply, then remove the battery, finally set the CMOS jumper to CLear CMOS. Wait at least a minute, then replace the battery and then the Power Supply.

Switch Back on, the first time you boot it will load default settings.

Reboot once windows is up and see if you get the CMOS error again.

Greg Palmer
Free Software for Adminstrators
 
Greg, I did what you said and left the battery out and cleared the CMOS memory again. I go into the bios and put in the right time and date, then I go to bootup. I don't get any errors that say "CMOS settings wrong" or "CMOS battery low", and it goes to boot up and it just freezes at that black screen. I push the reset button and the same thing happens, except the screen comes up that says windows did not shut down properly and asks you what you want to do: safe mode, safe mode with networking, same mode with command prompt, and start windows normally. If I click on start windows normally, it just freezes. If I click on any of the other 3, it comes up listing all these files that are loaded, and freezes on the last one. About 1 in 10 times I can click on start windows normally and XP Pro will boot normally. I have no idea what would control the bootup that would cause it to freeze. You would think the black screen would say "missing ntdlr" or "error loading OS" if there was something wrong with the MBR. Think a new installation of windows would help or is it something screwy in the MB.
 
If you are now happy that the CMOS situation is sorted, then yes i would recommend a full new installation of windows xp. Unless there is any data you need to save on the HD I would delete any partitions you have on your Drive and then create a new one(s) to match your needs.

Take a look at for details on formatting etc..

Greg Palmer
Free Software for Adminstrators
 
Thanks Greg, I am in the middle of an install right now. Can you have a look at this link from ECS and see if it could be a bios issue that I am having by looking at the fixes in each version, particulary the first one. It sounds like it may have something to do with the error, but I am not sure. I know the bios I am running is from late 2001 - early 2002, so it probably should be updated anyway. Also have never done this before and there are no instructions on their website, what kind of job is it? I wonder if it is XP based and I can just run the executable program from there, probably too simple in this case.

 
Bios updates are very simple, take a look at for details.

It also sounds like you are correct in the fact that a BIOS update might solve your problem.

I would go for it, there has been several months since it was released so if there were any problems with the upgrade they would have been released by now.

Greg Palmer
Free Software for Adminstrators
 
Finally I think I have gotten it. I updated the BIOS to the most current version, not nearly as bad as I thought it would be. The computer boots up fine and I also noted that my LAN connection is a lot faster than before, so I definitely think there was something weird going on with the BIOS. Thanks for your help Greg and I hope this thread can be marked as finished now.
 
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