12v CPU connector melted

[rbuce7540]

I have a Cyberpowerpc built system that uses a Gigabyte 970A-DS3P MOBO with an AMD FX 8350 Vishera 8 core CPU and a GEFORCE GTX 760 display adapter, all powered by a 600w power supply. Recently the 12v CPU connector melted at the two yellow wires side only and at the connector only...the wiring was not noticeably affected. There was no external power spike and the plug did not arc, it simply lost contact and the computer reset and would not POST. I replaced the melted plug parts and powered my system back up to see if it was fried, I got lucky, it was not. So next I checked the system board while it was operating, using a thermal camera to see what parts were getting hot...the 12v CPU connector was getting hot and the small square chip that is above and to the left of the CPU was getting rather hot for something that has no heat sink on it. I also checked CPU temps and they were steady around 60C and spiking up to 90C so I shut it down before the CPU melted down. I removed and re-installed the 600w PSU in another multi-core system and it is working fine there and the plug is not heating up, also teh voltages appear to be in the correct ranges. I am assuming that the CPU is still ok but I can't know for certain without another AM3 socket motherboard to test it on. I am thinking that something on the motherboard failed and was drawing too much current through the 12v CPU connector thus overheating it to the point of melting. I did some research and am now aware that this motherboard is not the best choice for an 8 core, but that is how it came. I bought the system in early 2014 and it has worked without any noticeable hardware issues until now. Anyone have any input or ideas about what may have caused this?

 

[Ecky]

The thing on the motherboard drawing too much current was the CPU. AMD FX CPUs are notorious for killing motherboards, due to their high power draw. Improved case airflow, or airflow directed at the hot areas on the board can help. You might also try undervolting and/or slightly underclocking your CPU to improve things.

 

[rbuce7540]

Ecky - While I do agree that the CPU was likely stressing the Motherboard's capabilities, I still have doubts that the CPU caused the 12v CPU power connector to melt simply because it was operating for over 2 years without that level of heat at the 12v CPU power connector. Something else had to have failed to cause such a dramatic and sudden rise in current draw to the point of melting the plastic. When I replaced the plug and turned it back on i noticed heating at the plug again and when I switched it back off and unplugged the 12v connector again, It showed signs of dangerous overheating again...the plug was slightly brown around one of the connector pins. Like I said in my first post, I re-installed the PSU in a different computer and that same plug is not heating up in that one, so it is definitely something on the motherboard in the power regulation and control circuitry that has failed....just don't know precisely what, although I am tending to think maybe one of the MOSFET's may have gone bad.

 

[Ecky]

Although you may be right, consider that heat increases electrical resistance, which in turn increases heat. If the traces on the board have degraded from heat, their resistance will be higher now, and they'll be more prone to getting hot again.

 

[Shaun o]

The more current you try to draw down a wire, that is only rated to carry a set amount of amp rating and wattage the more it will heat up.

Thinner gauge wire often used in cheap power supply's is often the cause, the thinner the wire used, or the amount of copper strands used to make the wire causes more resistance along a wire because the electrons bump into each other or become bunched tightly together.

The thicker, or more copper strands you use in a wire the less it will heat up because the electrons can flow more freely without bunching up with larger gaps between each.

If you have ever looked at a electrical bar fire you will see it is a very thin wire wrapped around a ceramic rod, where the wire is made of tungsten when you restrict electrical flow of electrons as said they begin to squash or pack together
The result of it is the wire it`s self begins to heat up due to the flow of the electrons being slowed down.

It is also how in old light bulbs where a fine tungsten filament is used how the bulb gives off light.
Resistance to electrical flow or the electrons from the voltage being supplied being bottle necked.

The more power you try to draw down a thin wire, say for example if you were overclocking the cpu at the time the more likely the wire will heat up and the outer insulation melt of the wire.

Wire is rated in the AWG gauge where the value, or number printed on the insulator of the wire will indicate how many individual copper strands are used to make the wire and how thick the inner copper core is.

Based on the amount of single strands used the wire is rated to carry a set amount of amps or wattage, voltage.

 

[Flying Head]

The connector is heating because of a poor contact. Since the connector at the motherboard is discolored, then perhaps there is a cold solder joint at the motherboard (see https://learn.adafruit.com/adafruit-guide-excellent-soldering/common-problems) . Remove the solder by suction or wicking and re-solder. The heat could have also oxidized the contact or changed its temper or tension making it loose. That would cause an even worse connection and higher resistance. The contacts have a rated current based upon the contact resistance. Since it is using two wires for that particular voltage, if one became bad then the other would be forced to pass all the current, which would cause it to overheat. The header on the motherboard needs changing too. Do you feel like changing it? Maybe you can find neighborhood technician or Engineer to do it.

Update: Note that the "connector melted at the two yellow wires side only and at the connector only...the wiring was not noticeably affected." Look at this:https://bitcointalk.org/index.php?topic=102890.msg1128322#msg1128322