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CMOS Battery Failure?

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October 27, 2011 4:28:23 PM

Need some help with this problem.

My computer has worked fine for the past 4-5 months I've owned it until I opened the case to install a case fan on the top. Simple. After installation, I powered the PC back up and got an error message on the BIOs screen saying: "CMOS Battery Low" and "CMOS Date/Time Not Set". I set the date and time and continued as normal. Everything was fine except I could no longer see any icons in the notification area. Changing the Bios date/time didn't seem to do anything as the PC's system date was still wrong; off by about a year.

On some advice, I kept the PC running for 24 hours to charge the CMOS battery, and finally restarted the PC due to a system update from Microsoft. The PC turned back on, but I couldn't see anything from the monitor, and did not hear the 'beep' from the motherboard. I made sure it wasn't my graphics card by swapping, which did nothing. I bought and replaced the CMOS battery with a new one, and powered the PC back on and I got the same two error messages at the BIOs screen. After updating the date and time again, I continued to logon no problems, however I still can not see my notification area and I still had to manually change the system date and time.

What happened to the PC?? I thought that by changing the battery the issue would go away but it doesn't seem to have done anything. What do I need to do to fix this problem? Is this a sign of the motherboard going bad? Any support would be appreciated.

BIOSTAR A770E3
PH II X4 955 Black Series 3.2Ghz (unmodified)
Rendition DDR3 10600 12 GB (unmodified)
Nvidia 450 GTS (unmodified)
Antec 550 Watt PSU

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November 3, 2011 1:44:17 AM

I ordered a replacement motherboard and installed it, no problems. I haven't a clue what happened to the other board though... plan to investigate.
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a b V Motherboard
November 3, 2011 2:30:42 AM
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Most current motherboards use a CR2032 3v Lithium battery for the CMOS battery. The purpose of the battery is to maintain enough power to the CMOS memory to keep the system configuration and clock accurate. It does not get charged up when the power to the motherboard is left on because it is not a rechargeable battery.

In the past, many motherboards did use a rechargeable battery to save the CMOS from being lost but this is no longer necessary because modern CMOS memory requires so little power to maintain valid data. A very small battery can be used to keep it valid for months to years.

When you replaced the CMOS battery you removed the old one which caused your CMOS to lose power and, therefore, the data and the clock became invalid. Then you installed the new one which restored power but did not restore the lost data or clock. So when you powered on the system the CMOS data was again in the invalid state and needed to be rewritten by the BIOS program. All of this is normal and does not indicate a problem with your motherboard.

However, the following statement, "Everything was fine except I could no longer see any icons in the notification area. Changing the Bios date/time didn't seem to do anything as the PC's system date was still wrong; off by about a year.", could possibly indicate a problem, most likely with windows. I have seen this particular issue myself several times after I have been working in the BIOS. Windows, for reasons that I have never understood, sometimes fails to update the date/time correctly. I wouldn't worry too much about that as long as the date/time stays current and correct after you set it in windows..

However, the fact that you lost your icons in the notification area suggests that something got corrupted in Windows. Which version of windows are you running? Can you describe in better detail what exactly you're not seeing? Is it just the icons or is the entire notification area missing? I assume you're referring to the small area in the lower right hand corner next to the date/time display, correct? Does the rest of your Desktop come up OK? Does your Startup menu appear correct or are there items missing? Also look at the devices in Device Manager to see if there are any devices that are not working or cannot start.

Additionally, in your second post you said that everything is good with the replacement board? But, is the replacement the same board exactly or is it a different model or manufacturer?
November 3, 2011 2:47:32 AM

I am running Windows 7 64-Bit Professional. And yes, the replacement motherboard is the same exact model (Biostar - A770E3).

When I was referring to the notification area, I could only see the volume icon, and nothing else, although they were still there I suppose. I expanded the tray and though I couldn't see the icons, their spaces were there... almost like placeholders, but I couldn't interact with them(Right clicking, Left clicking, accessing through the control panel- nothing.)

Out of curiosity, I want to know what happened to the board; Thinking back, when i installed the case fan, I plugged it's power cord directly onto the motherboard, like I had with all the others. I do recall seeing dust shoot up, at the time I ignored it... but perhaps it was smoke? Maybe I somehow shorted out that area of the board... even though the power supply was unplugged.

Here's the board, you'll be able to see where the CMOS battery is:
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
a b V Motherboard
November 3, 2011 3:43:13 AM

Hmm, since you replaced the board with an exact replacement model and now it all works, then you likely damaged something when you plugged in the new fan. "Seeing dust shoot up" could mean you popped a capacitor. Some likely possibilties would be ElectroStatic Discharge (ESD) or inadvertantly shorting something that still had some electricity stored by a capacitor. Did you have the rocker switch on the back of the PSU turned off? If it was on that may have been what caused the damage.

Whenever I work inside my computer I am careful to avoid ESD by keeping my PSU plugged in to a grounded outlet with the PSU power switch turned OFF and I always make sure to touch the case metal before reaching in to touch any components inside the case. This will ground me and remove any static voltage from my body thus avoiding discharging current through sensitive components. (Some people will disagree with the idea of having the PSU plugged in but it's only dangerous if you have the PSU opened up. Never open or remove the PSU with it plugged in.)

It's also advisable to work on your computer on a clean table or desk that does not sit on a carpeted floor because carpet can cause you to build up static very quickly.

Some other good practices: Take your time and think by going through a mental checklist, ie, power off, power switch off, touch case to discharge static then work on computer.
Take your time when inserting and pulling cards and components and treat your components gently.
Always check cable orientation before attempting to insert. (Hmm, are you sure that you didn't insert the fan connector backwards?) Most connectors are keyed so forcing a connector will often break something. Don't be afraid to use firm pressure just don't force it.
Recheck everything you did before restoring power to make sure that you didn't overlook something or make a mistake.
November 3, 2011 3:54:55 AM

Oh trust me, I was working on my PC in a very safe area. I was wearing static guards and was working on a wood tabletop. I always take special care when dealing with electronics... however I do think I left the rocker switch on the PSU... gah. I never force a component or wire. My philosophy is if gentle force isn't doing it, your doing it wrong. Atleast with computers.

Oh well, atleast everything is alright now. Don't plan on adding anything new to my setup for awhile. I appreciate the replies JKatwyopc, and davcon.
November 3, 2011 3:55:12 AM

Best answer selected by joe0079.
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