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CMOS overheating?


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#1 Netghost56

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Posted 25 August 2014 - 11:21 AM

Has anyone ever witnessed this issue?

 

I have a system (Core 2 Duo, 2.5GHz) on the bench, no owner as it was donated by an office along with others. No HDD either. It has a aftermarket Coolermaster 460w PSU- the kind we sell out of our office. I added a 500GB WD IDE and started to install XP Pro (case has the key) and the system would shut down during the initialization setup. It would not power on until I had unplugged and re plugged it in. Obvious sign of overheating, right?

 

I still have the case open, so I started checking connections and I could immediately feel a lot of heat radiating from the PCI slots and the CMOS battery. The battery was so hot it burnt my fingers, but the heat seems to be originating around the PCI slots. I can't find any evidence of bad caps, burnt connections, shorts, or otherwise.

 

I swapped out the battery with a working used one just in case the battery was somehow bad (shorting?) but same issue persists.

 

My question is this: Could the PSU be pushing too much voltage, or dirty power? Or is this an obvious bad motherboard?

 

I don't know anything of its history, except that the system was hand-built, probably by us, a few years ago.



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#2 mjd420nova

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Posted 25 August 2014 - 12:37 PM

A multimeter would offer more clues to the power supply fault but a close inspection under as good magnifier could reveal the problem.  A check of jumpers (especially the "reset" jumper) might provide a clue.  It may reveal someone overclocked things beyond their heat specs.



#3 synergy513

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Posted 25 August 2014 - 12:39 PM

socket 775 motherboard make/model?

 

i don't recall reading about this high heat from a cmos battery. i know that a motherboard northbridge can get super hot though. hence the heat spreader on it. sometimes they have a dedicated small fan on them. the northbridge  is where the traffic from the cpu to the PCI slots is routed through.

 

you can try to swap in a new corsair power supply to check if that is the culprit. power supplies do get heat-related wear over a span of years.

 

also, the power supply provision to the motherboard is usually a 4 pin and utilizes a separate voltage, if i recall correctly.

 

what happens when you get into the BIOS and check for the settings there?


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#4 Netghost56

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Posted 25 August 2014 - 02:15 PM

It's a Intel DG31PR. Yeah, I posted it because I've never had one with a heating issue like this before.

 

I have tried a different PSU but no change. Still looking at the BIOS. I swapped out the battery which should have removed any OC settings.

 

I've isolated the source of the heat (with war wounds to show for it!)

 

It's the silver resistor piece. The caps nearby were pretty warm too.

 

CORRECTION: It's a crystal oscillator. Has 25.0 MHz written beside it.nyttgh.jpg


Edited by Netghost56, 25 August 2014 - 02:32 PM.


#5 synergy513

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Posted 25 August 2014 - 04:21 PM

strike a blow for the practical approach....

 

i haven't heard of that little component causing trouble before...duly noted


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#6 dpunisher

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Posted 25 August 2014 - 04:55 PM

Something of that vintage, look over those caps, especially the ones by the CPU socket near the VRMs.  I have replaced some capacitors on those in the past (until I found really cheap refurb boards out of Hong Kong).

 

EDIT:  Well, I looked at a few different pics of that board and all of the caps near the CPU look like KZG/Chemi-Cons.  Those usually don't cause problems.  No telling, maybe Foxconn  kicked out a bunch of intel boards with cheap caps.  You never know till you check....good luck.


Edited by dpunisher, 25 August 2014 - 05:03 PM.

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#7 mjd420nova

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Posted 25 August 2014 - 07:18 PM

Alot of the times the crystal device will be soldered to a patch to help with the heat.  Some only need a small wire soldered to the top and to the board to act as a heatsink.  I'm still interested in any voltage readings. 



#8 Netghost56

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Posted 26 August 2014 - 09:05 AM

I took a snapshot of the readings in BIOS, right after powering on after letting it set overnight.

 

5.0820

12.1440

1.2590

1.1880 (VcoreA)

 

CPU temp was 20 and Motherboard was 54 upon boot.

 

After 5 mins:

 

5.0820

12.2050

1.2672

1.1880

 

CPU temp was 28 and Motherboard was 71.

 

If there's no other info needed, this afternoon I'm going to remove the board from the case and do a detailed inspection.



#9 Netghost56

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Posted 26 August 2014 - 03:16 PM

Update:

 

Front side:

 

35d0zft.jpg

 

Back side:

 

2mfnj2u.jpg

 

Apparently something melted beneath the Realtek chip. I broke off a burnt piece of what appears to be plastic around the solder points. Here's a hi-def image. Mystery solved!

 

4qo488.jpg



#10 mjd420nova

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Posted 26 August 2014 - 07:09 PM

The only thing I can think of would be a small cylinder, like a standoff, but wrapped in foil to provide a groundpath and heatsink of sorts.  Not seen that technique in a long time..  Surprised you didn't get any smoke signals.






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