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Motherboard fire after changing CMOS battery

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June 23, 2012 8:40:06 PM

I have a few issues going on. I have the original issue described below, followed by the fire while working on the original issue. Any help regarding either would be surely appreciated. I don't know if the two are related.

Here are the issues:

I have an older system that stopped POSTing the other day. I would get all fans and LEDs, but no POST beep and no video.

RAM (4 sticks,) video card, CPU all checked out fine in another system.

I breadboarded (kept in CPU/heat sink/fan, 1 stick RAM, video card, PS) and checked the following:

If I took out all the RAM, I would get the correct beep code for no RAM. This was true with or without video card in.

If I put the RAM back in (any stick, even known working stick from another machine,) I would get no beep code - no POST - and no video, either. This is true with or without video card in.

I also used a multimeter to test power supply. It fell into tolerances, but I know that's not the be all and end all.

I did some Googling and decided to reset the CMOS as some people said they had success with this. I figured the battery was old, so while I was at it I put in a new battery.

As soon as I plugged in and turned on the power supply, the board started up on its own, without me needing to short the Power On pins. This was not the case prior to changing the battery. Before that, it DID require that I short the Power On pins to start up. As soon as it started up, the board caught fire between the battery and the CMOS jumper pins.

I am curious as to why this would happen. I'm looking at the board right now, and the battery is correct, and seated correctly. Why did this not happen with the old battery? Was there possibly a voltage regulation issue with the board the whole time causing all the issues, and it just culminated in this event after getting a new battery?

The board is an older board - Intel D945pvs with a Pentium D 830 chip and 4 sticks of DDR2 RAM. The board was NOT overclocked at all.

So, any thoughts? Thanks in advance for any help/insight people can offer.
a c 478 V Motherboard
June 23, 2012 8:47:57 PM

i dont think it was a cmos or battery issue. i think your mb bios and mb saw a dead short and tried to save the mb by not powering up right. when you took the battery out the cmos lost all the data and went back to factory default. when this happened i think it bypassed the mb dead short safty and the defective power supply or shorted chip on the mb fried.
i would see if the mb under warranty and the ps and rma them if not take what you can from the old system and rebuild.
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June 23, 2012 8:53:44 PM

smorizio said:
i dont think it was a cmos or battery issue. i think your mb bios and mb saw a dead short and tried to save the mb by not powering up right. when you took the battery out the cmos lost all the data and went back to factory default. when this happened i think it bypassed the mb dead short safty and the defective power supply or shorted chip on the mb fried.
i would see if the mb under warranty and the ps and rma them if not take what you can from the old system and rebuild.


Thank you so much. Your answer makes sense, as my husband and I were sitting here discussing it, and were wondering something similar. It's an old board and an old PS, so no warranty for either at this point (both about 7 years old.) That's okay, as I can get a comparable board these days for a pretty low price. A short all along sure makes sense, though.
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a c 478 V Motherboard
June 23, 2012 10:38:44 PM

if your shopping for new parts..a small upgrade on the old pc will make it go a long way. i would look into a intel g620 and a mb for it. if not replacing it with a newer dell or hp with a newer amd or intel cpu the pc going to run a lot faster then the old system that died. 7 years was a nice long time for that pc. i had an older 775 mb and i can tell you the newer cpu with just the built in video are a lot faster.
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a b V Motherboard
June 23, 2012 11:01:43 PM

I don't agree with the above explanation for a number of reasons. the first being if the motherboard was not powered up due to a dead short then the BIOS would not be working so it couldn't do anything about it and second the BIOS does not work like that.
The fire could only have been caused by a short on the motherboard, was the clear CMOS link fitted in the clear position when the computer was connected to the supply? If so then this is the most likely explanation. Anyway the motherboard is now dead and a new motherboard will be required. As the processor is a dual core and unlikely to have been effected by the mishap it will probably be worth fixing.
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June 24, 2012 12:05:32 AM

smorizio said:
if your shopping for new parts..a small upgrade on the old pc will make it go a long way. i would look into a intel g620 and a mb for it. if not replacing it with a newer dell or hp with a newer amd or intel cpu the pc going to run a lot faster then the old system that died. 7 years was a nice long time for that pc. i had an older 775 mb and i can tell you the newer cpu with just the built in video are a lot faster.


This is not my main machine, and wasn't getting used much anymore. I was going to use it for a project. But, I still want to do it, so I bought a new power supply and will get a chip-compatible board. Not too much money to get something for an old chip like that. My main machine, though not brand new, it much faster. It's got the X58 chipset board with a core i7 1366 pin CPU. I built it about 3 years ago, I think, but it still performs really well.
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June 24, 2012 12:14:31 AM

pjmelect said:
I don't agree with the above explanation for a number of reasons. the first being if the motherboard was not powered up due to a dead short then the BIOS would not be working so it couldn't do anything about it and second the BIOS does not work like that.
The fire could only have been caused by a short on the motherboard, was the clear CMOS link fitted in the clear position when the computer was connected to the supply? If so then this is the most likely explanation. Anyway the motherboard is now dead and a new motherboard will be required. As the processor is a dual core and unlikely to have been effected by the mishap it will probably be worth fixing.


What I got out of that first response was that it was caused by a short. And, you are saying saying a short, too, which is what makes sense to me. Wasn't sure about the BIOS part, though, so thank you for that explanation. Y'know, the CMOS jumper was in the clear position. I'm looking at it now, and I hadn't moved it after the mishap, so I can see that it was in that position. Looks like I forgot to move it back. But, I wasn't at all aware that it could cause a short like that! Well, now I know. Your right, also about the CPU. It is testing fine in another machine, so I'm going to be reusing it.

I was curious, though, if a short was causing the original problem, or something else. Any thoughts on that?
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a b V Motherboard
June 24, 2012 12:33:43 AM

Quote:
I was curious, though, if a short was causing the original problem, or something else. Any thoughts on that?


That the original fault was to do with the motherboard seems clear although maybe the clear CMOS if done correctly would have fixed the problem who knows.
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June 24, 2012 12:39:56 AM

pjmelect said:
Quote:
I was curious, though, if a short was causing the original problem, or something else. Any thoughts on that?


That the original fault was to do with the motherboard seems clear although maybe the clear CMOS if done correctly would have fixed the problem who knows.


Thanks. Yeah...I feel really embarrassed right about now, that I didn't put the jumper back in the right place. I don't know if I got distracted, confused or what, but it's sitting there in the wrong position, so it seems clear that this is what happened.

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