FIRE! CPU power cable melted

[y3llowduk]

Errrr so an old gaming PC I was fiddling with to try and flip for a bit of cash started smoking! I was trying to diagnose an overheating issue with it hitting silly temperatures and throttling. It's an old i7 860 so I gathered the IHS thermal feces might be long since past its best (if it is thermal grease on this processor?) but was experimenting with other coolers etc. to see if I could cool it down.... until it started smoking. PC was running fine (albeit far too hot), I was literally about to stop the benchmark due it spiking up to 95/96c. PC stayed running while it was smoking while I scrambled to pull the plug. Upon inspection the 4-pin CPU power extension is the source of the burning. The rest of the cable looks absolutely fine. Can't see anything on the motherboard either :( What would cause such a thing? It has to be something to do with the excessive temperatures of the CPU as it did spike the highest it's gotten too before smoking! I'm pi**ed off as I was literally about to close the stress test due to the temperature and give up on this CPU (I had put back the intel stock cooler with fresh thermal paste to see if it would run any cooler with high quality fresh paste, after testing a fat aftermarket cooler with not much better results). I'm paranoid as I don't know exactly what would have caused this? The connector wasn't up against the heatsink or anything i'd expect to get hot enough to melt it. The only thing it is touching is the painted metal of the case, the part where it wraps around the motherboard, and maybe touches the motherboard standoff in the corner? Can't see anything burnt out on the motherboard?? The only thing I can possibly think of is one of the spike parts in the back of the motherboard somehow punctured the insulation on the cable but there was nothing putting excessive pressure on it??? h e l p.... Oh and PSU is a HP 460w from a Pavillion H8 with an Intel DH55PJ

[y3llowduk]

Something to note, the whole extension shows signs of melting and heat, not just that part with the bare wire

[Jurrunio]

8 minutes ago, y3llowduk said:

Something to note, the whole extension shows signs of melting and heat, not just that part with the bare wire

Then it's not due to high CPU temperatures, but the extension cable using wires that are way too thin

[mariushm]

That extension is made with thinner wires, AWG20 ... also, chinese extension cables often cheap out on wires by using steel or aluminum strands mixed with copper strands because steel and aluminum are cheaper tha copper... but the problem is that this increases the overall resistance of the wire so it heats more.

But a decent extension, with thicker wires, AWG18 is the standard, AWG16 would be ideal.

 

a more technical explanation : wires have a resistance... the more electricity flows through them, the more they heat up... that's why more power hungry processors use the connector with 8 wires.

Because of the 4 pin connector on the motherboard, your best option is to use a quality extension with thicker wires.

[y3llowduk]

OK thanks guys, that makes a lot of sense. I've had a closer look on the extension and the wires read "1007 VW-1 80c 300v 18AW YC-HX", would this suggest that it is AWG18? And here's a closer look at the section burnt to bare wire. it kind of looks copper colored but the bit where the burn was focused looks silver? Fake coating maybe or would copper possibly go this colour when heated?

[Kilrah]

Both positive wires got hot, so yes the cables are definitely not thick/conductive enough to supply that system. PSU was likely made for something much less demanding.

[Dirtnapper]

 

Could not help myself, glad its doesnt look to bad other then wires

[mariushm]

It could be tinned copper but I doubt it, most likely it's steel strands (as i said, steel is cheaper than copper but has higher resistance)

 

1007 refers to UL1007 standard wire and WV-1 is just a rating related to how well the cable insulation resists flames and self extinguishes (vertical flame test : http://fr.polymerinsights.com/testing/flammability/vw-1 ), 80c refers to maximum rated temperature and 300v is obviously maximum voltage.

The YC-HX may be a rating of the company that makes the cable that would differentiate it from cables made with other cables made with different number of strands and so on.

 

You can make burn tests or use magnets to detect type of wires

aluminum (copper clad aluminum wires are common in cheap ethernet cables) will shrink and twists when under flame (you can put stripper wire with aluminum under lighter flame and it will shrink and twist or bend right away

copper will remain the same.

Unless I'm mistaken, steel wire will be attracted by magnet while copper wire should not be... but I may be wrong.

[y3llowduk]

15 hours ago, mariushm said:

It could be tinned copper but I doubt it, most likely it's steel strands (as i said, steel is cheaper than copper but has higher resistance)

 

1007 refers to UL1007 standard wire and WV-1 is just a rating related to how well the cable insulation resists flames and self extinguishes (vertical flame test : http://fr.polymerinsights.com/testing/flammability/vw-1 ), 80c refers to maximum rated temperature and 300v is obviously maximum voltage.

The YC-HX may be a rating of the company that makes the cable that would differentiate it from cables made with other cables made with different number of strands and so on.

 

You can make burn tests or use magnets to detect type of wires

aluminum (copper clad aluminum wires are common in cheap ethernet cables) will shrink and twists when under flame (you can put stripper wire with aluminum under lighter flame and it will shrink and twist or bend right away

copper will remain the same.

Unless I'm mistaken, steel wire will be attracted by magnet while copper wire should not be... but I may be wrong.

Thanks, I'll try get hold of a magnet to test it. Do you know any good brands I could get some better quality extenders from?

[nafiz mahmud]

I also had the same problem and my extension melted. and it is not coming off of my cpu original power cable. what do to??? thanks in advance. please suggest me something to make the cable off of my psu cable.