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Question P4 connector burnt

Jul 28, 2021
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Motherboard- Intel DG33FB
RAM- Transcend 2 GB
Processor - Intel Core 2 duo (LGA 775)
PSU- Intex ATX 2.03 450 WATT

I have been running this system for the past 13 years. For the past few days, my system was randomly switching off on its own after a few minutes of usage. I blamed RAM for it and opened my tower and cleaned the RAM and reinserted it. I turned on the power and something popped inside the case and a spark came out. I instantly switched off and checked what happened. After much of the inspection, I found that one of the four wires of the P4 (2x2 connector) was hanging out with black burn visible.




The 24 (2x12) pin is completely fine and no other damage can be seen on the mobo. All fans were completely fine and temperature was normal before.
I tried another PSU (400watt) and no boot.
I can only see motherboard light but nothing else.
I think using a cheap Intex PSU caused the problem. Is my Motherboard okay?
Any comment will be much helpful please
 

lvt

Commendable
Apr 19, 2021
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Are you sure that the other PSU still work fine?

Another thing to try is to use a Molex to 4-pin CPU cable to replace the burned connector.

Also check and clean the 4-pin connector on the motherboard, there might be some residue that prevent a good connection.
 
Reactions: Zaricon
Jul 28, 2021
5
0
10
0
Are you sure that the other PSU still work fine?

Another thing to try is to use a Molex to 4-pin CPU cable to replace the burned connector.

Also check and clean the 4-pin connector on the motherboard, there might be some residue that prevent a good connection.
Hey, thanks for your reply.
Now, just to check whether the PSUs are working, I performed the paper clip test and fan didn't turn on on both the PSUs. I even checked with tester and the clip was receiving electricity but still the PSU fan didn't turn on. Now how can both the PSUs go bad at the same time. I remember I oiled the PSU fan and cleaned it thoroughly and both worked fine.

Note: the other PSU is from another CPU which had already stopped working 4 years ago. So maybe it has been dusted out and not working.

Also, as seen in the picture, no residue is left on motherboard since the connector has no stains, only the wire has come out with black burns. Everything else is alright.
 
Replacing the PSU leaves the other end with the motherboard connector possibly still coated with not-very-visible melted plastic deposits, as lvt mentioned. It's pretty difficult to clean those pins off with any type of sanding tools without destroying the plastic. The pins are also shaped to be kind of springy and the high temperatures could have deformed them

Given the age and low value of the board and PSU, it would make sense to just directly solder the original PSU's P4 connector wires to the motherboard to eliminate any chance of a high resistance connection. If you have any sort of P4 extender wire around, you could solder that to the board instead to effectively replace the connector and thus be able to easily change PSUs

As for why the board fails to turn on (and possibly why the wires burned), one of the VRM mosfets could have failed with a dead short. It's easy enough to check each with a multimeter for continuity. That's of course if you are testing the PSUs with the paperclip when the board is plugged in.
 
Reactions: Zaricon
Jul 28, 2021
5
0
10
0
Replacing the PSU leaves the other end with the motherboard connector possibly still coated with not-very-visible melted plastic deposits, as lvt mentioned. It's pretty difficult to clean those pins off with any type of sanding tools without destroying the plastic. The pins are also shaped to be kind of springy and the high temperatures could have deformed them

Given the age and low value of the board and PSU, it would make sense to just directly solder the original PSU's P4 connector wires to the motherboard to eliminate any chance of a high resistance connection. If you have any sort of P4 extender wire around, you could solder that to the board instead to effectively replace the connector and thus be able to easily change PSUs

As for why the board fails to turn on (and possibly why the wires burned), one of the VRM mosfets could have failed with a dead short. It's easy enough to check each with a multimeter for continuity. That's of course if you are testing the PSUs with the paperclip when the board is plugged in.
Thanks a lot for your reply.

As I said, I checked the PSU by inserting a piece of Aluminium wire (thick tho) and the fan didn't turned on, though it showed a very slight movement on rotating it with a stick. But, both the PSUs turn on the small green bulb on the motherboard. I don't know if the PSU or motherboard is alright or not.

Also, the connector wire popped just after turning on and I instantly turned off the power, all within 3 seconds. So i think contacts would be pretty much alright (from a novice perception).
 
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