Question Molex connector for fans touched case, small spark and pc shutdown but starts up fine after. But...

Apr 11, 2020
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Long title, sorry.

So I replaced/upgraded my cpu and mobo and ram. Everything went smoothly. Until I was plugging in my last case fan into a molex connector using a peripheral cable from my psu.

Fan went on, then I was putting the cables back in my case and there was a small spark and everything turned off. It turned back on once I switched my psu on and off and after a few tests of reboots everything seems fine except the case fans wont turn on from that molex anymore and I'm too afraid to plug them into my mobo now. All the usb ports work fine on the case, all the other parts are running fine (cpu, ram, gpu, temps are fine) just the case fans that used the molex/psu peripheral cable wont turn on.

For now I took out that cable from the psu and the molex connectors and just not using the case fans for now. I can try plugging them into the mobo but I dont want to damage the mobo if nothing affected it already.

Any experience with this? Did i just fry the molex and peripheral cable? Any chance or likelihood of something worse?

My psu is an EVGA G3 650. From what I read the surge protector kicked in most likely and thats all I lost were the cables. I may buy a new case out of paranoia.

Anything would be great, thank you.

Also, psu was plugged into a surge protector if that matters. As for all the components that seem to be working fine, is there anyway to test if they arent? Are the case fans safe to plug into the mobo after that?
 

RealBeast

Titan
Moderator
I think you now see why you always turn the PSU off or unplug it when working on connections.

Visually inspect the Molex and cable -- it is unlikely that part acted as the weak point. More likely the Peripheral port of the PSU is damaged.

An external surge protector would have no value for this occurrence.

Most likely the fans are not short-circuited (that would allow them to damage the motherboard), although I would test them with my multimeter (and the PSU Peripheral port too as well as the cable just to determine the actual problem).

I err on the side of caution so I would run the fans on another 12V DC source like some batteries as a test to insure that they run, but they will probably be okay to run on the motherboard headers, which supply 12V.
 
Apr 11, 2020
3
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10
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Visually inspect the Molex and cable -- it is unlikely that part acted as the weak point. More likely the Peripheral port of the PSU is damaged.

An external surge protector would have no value for this occurrence.

Most likely the fans are not short-circuited (that would allow them to damage the motherboard), although I would test them with my multimeter (and the PSU Peripheral port too as well as the cable just to determine the actual problem).

I err on the side of caution so I would run the fans on another 12V DC source like some batteries as a test to insure that they run, but they will probably be okay to run on the motherboard headers, which supply 12V.

Ok much appreciated. I dont have anything to test the port of the psu but from what i see they are cheap enough and obviously something i should have on hand after this lesson.

My biggest concern is if a psu with a damaged port is still safe to use? Like I said, my entire pc boots up and runs fine. I'm just concerned about the overall function of the psu. I can live without using a peripheral cable port.

Thank you again
 

RealBeast

Titan
Moderator
Ok much appreciated. I dont have anything to test the port of the psu but from what i see they are cheap enough and obviously something i should have on hand after this lesson.

My biggest concern is if a psu with a damaged port is still safe to use? Like I said, my entire pc boots up and runs fine. I'm just concerned about the overall function of the psu. I can live without using a peripheral cable port.

Thank you again
Until I tested the PSU port I would suspect it is damaged, and while the Perif port should just be dead I can't guarantee that it cannot damage anything else. The PSU sounds to be working otherwise, however it is not possible to say what exactly happened other than something was damaged by the short circuit created momentarily.

Long ago I learned this lesson attaching a molex cable to a HDD (like I said long time ago), had it powered on and upside down, spark jumped and the HDD chips all bubbled up on the surface. That was pretty easy to diagnose. 💩
 
Apr 11, 2020
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Until I tested the PSU port I would suspect it is damaged, and while the Perif port should just be dead I can't guarantee that it cannot damage anything else. The PSU sounds to be working otherwise, however it is not possible to say what exactly happened other than something was damaged by the short circuit created momentarily.

Long ago I learned this lesson attaching a molex cable to a HDD (like I said long time ago), had it powered on and upside down, spark jumped and the HDD chips all bubbled up on the surface. That was pretty easy to diagnose. 💩

Ok thank you again. Next purchase is a multimeter. After so many years I got too complacent and thought i knew enough for this to not happen. Ah to be humbled.
 

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