CPU power extension burn out !

Nickjf20

Nickjf20

Nickjf20

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Joined
6 Apr 2012
Posts
278
Hi,

I've had the machine in my sig for a while now, it was bought second hand for a very reasonable price, but when in the new case, the PSU wire to the CPU was too short - so I bought a £1.62 extension off eBay.

A few months back I had a look in HWMonitor, and it said my 12V rail was stuck at 13.44V, so I ran Prime95 to check with a multimeter - voltages were fine (12.05V) but there was a burning smell I couldn't locate properly. I left that down to dust on the cheap (read - OEM ****) RAM that gets reasonably hot. I cleaned the RAM and left it alone.

It's been working fine for a while now, but today I was rendering some videos / playing BF3 and the burning smell returned, this time with some electrical crackle ! :eek: I turned off the PC as anyone would, and opened it to find smouldering plastic on one of the extension wires.

I doubt it's damaged anything, unless the electrical crackle was shorting and damaged the PSU - I don't know.

Now, I can either buy another extension from a more reputable seller, or upgrade the PSU from the (again OEM) Lite-ON 450W thing that's currently in use.

I was thinking about an OCZ ZT 750W PSU as it's a pain changing the PSU in the Powermac case and wanted something I could use for years, possibly adding dual cpu, sli etc etc ...

http://www.ocztechnology.com/ocz-zt-series-550w-750w-power-supply.html

Any recommendations for PSU / what to do ?



Pics of the burn http://www.flickr.com/photos/nickjf20/7181575464/in/photostream/
 
Upgrade PSU if it was running high its the psu and not the extention cable. Theres one on offer today from CoolerMaster which i would highly recommend
 
The PSU voltage wise is running fine as tested with a multimeter - HWMonitor was off.

I think it's down to the extension cable purely because it's localised to the one area of the extension cable, rather than a general melt along the length of original PSU cable + extension.

As for the PSU, I was hoping for one with 4 PCI-e connectors.
 
It looks like it has burnt out due to a poorly made joint at one of the connectors, I'd also check for signs of heating at the connector which mates with that one (whether that be on the PSU or on the motherboard)

Its likely to just be a poorly made extension cable, but any joint or connector has the potenial to fail. If you are competant, you might consider cutting the leads on teh original PSU and lengthing by getting some suitable CSA wire (find a PSU in a skip or something), and making some sound solder joints and sleeving with heatshrink. Best not do it unless you know one end of a soldering iron from the other though, the joint has to be made soundly or it'll lead to heating and failure again
 
Adam_151 said:
It looks like it has burnt out due to a poorly made joint at one of the connectors, I'd also check for signs of heating at the connector which mates with that one (whether that be on the PSU or on the motherboard)
Click to expand...

Then it would burn out at the connector then and not along the wire surely?

I'm guessing that the extension cable isn't proper rated cable which is why it was cheap and it can't handle the current that was flowing through it.

Is it 18AWG? Either way I'd still get a better made extension cable not from eBay and try it. If that cable also burns out then it could be the PSU causing the damage.
 
GrimsbyLAD said:
Ide still suspect the PSU as its an odd place to burn tbh :/ But try a better extension first i guess
Click to expand...

+1

Its an over current problem, either the wire can't cope with the load, or I also suspect the psu as the culprit.

And Lite-ON psu's:( no experience of them,but I would trust a well known branded make like OCZ,Corsair, Antec, etc first.

Can't go wrong Asaka power cables, cost abit more, but you know there good quailty, ocuk stock them.
 
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moogle said:
Then it would burn out at the connector then and not along the wire surely?
Click to expand...

If would heat uniformly along the wire then, and perhaps slightly less closer to the connector, and it would also heat the associated ground conductor.

What you seem to have is a burnt bit of wire very close to the connector on one conductor only. This appears consistant with localised heating in the terminal being conducted back through the copper. The terminal itself might have escaped too much damage due to having a larger thermal mass through to disapate the heat, expecially if its the motherboard end... power busses on boards are normally done as 'planes'.... layers of the board which are all track except for where components have to pass through, which will act very much like a heatsink. That doesn't mean the connector won't have risen above its design tempature though!
 
Well I mean the plastic housing doesn't seem to be discoloured or melted from what I can see, it does have a slight dark tinge but it's not really clear.

Usually heat at the connections yellow them or there's some melting.
 
Thanks for the replies

It's weird, there isn't any discolouration on the the plastic housing, nor on the actual motherboard connector.

The way in which the copper almost looks to have burnt and snapped at a single point suggests it may just have been thin in that area. I've checked and the wire is 18AWG, all other specs identical to the original PSU wire, including manufacturer interestingly enough.

The current PSU has 2 12V rails, each up to 18.5A, total not exceeding 32A. I think putting a 7850 on it will be pushing it, especially since it's essentially unbranded/generic (Lite-On not being particularly well known r.e. PSUs)
I might overclock my 920 a bit as well, and I've been thinking of a new PSU for a while simply for sleeved cabling.

Since I can't use the PC at all until this is fixed, I'm going to order a new PSU asap.

Does anyone see anything glaringly bad about the OCZ ZT 750W psu ?
 
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