Spark shuts off PC (cables suspected)

[Dartmouth]

I recently had trouble with my pc not turning on. Thinking it my heat sink & fan at first (I tried to reseat it cause it was rattling a bit and I noticed one of the pushpins was broke), I replaced it with a Evo 212. It was running again until I pushed back in some loose cables and something sparked and it shut down. I believe the spark originated from around the loose cables but I can't say this with 100% certainty.Stupidly I did this while it was on but I did not think it would be an actual issue being just unused molex connections and such. I was able to get it back on but I am being careful not to touch anything and ruin my luck.

So I am wondering what could be the issue...
Loose connection?
A cable end touching the wrong thing?
Static?

I also removed an exhaust fan I was using thinking it may just be old and shoddy. The fan worked but I wanted to be safe.

 

[thx1138v2]

There shouldn't be enough voltage on any of the wires coming out of the PSU to spark anywhere so it depends on where the spark occurred. If you are in a very dry climate and can scuff your feet across the carpet and get a spark to your hand when you reach for a door knob it was probably static electricity. If that's the case I'm surprised you got it to boot up again. I had a friend who kept his computer on a carpeted floor. He crawled under his desk to plug in a new keyboard one time and a spark jumped from his finger to the keyboard socket. It toasted the motherboard so be careful if you have high static electricity.

On the other hand, a spark inside the PSU can not be good. If you start having heat or power shutdown problems it will be time to replace the PSU.

 

[Dartmouth]

There shouldn't be enough voltage on any of the wires coming out of the PSU to spark anywhere so it depends on where the spark occurred. If you are in a very dry climate and can scuff your feet across the carpet and get a spark to your hand when you reach for a door knob it was probably static electricity. If that's the case I'm surprised you got it to boot up again. I had a friend who kept his computer on a carpeted floor. He crawled under his desk to plug in a new keyboard one time and a spark jumped from his finger to the keyboard socket. It toasted the motherboard so be careful if you have high static electricity.



On the other hand, a spark inside the PSU can not be good. If you start having heat or power shutdown problems it will be time to replace the PSU.

Well it is pretty dry here, but it didn't seem to come from my hand. I did not feel anything and it looked like it originated from the front bottom interior. Although I believe I was just pushing the cables I may have inadvertently touched the case itself without noticing. If it is static could such a situation be possible? And how could I prevent a repeat of this?

Also you mention that a PSU cable could not cause this. Are there any others that could?

 

[unksol]

The PSU has PLENTY of voltage to cause a spark. And that is exactly what happened. Ever seen a car battery short? It's 12V too. A short will cause a large spark and melting of wires and metal if allowed to continue. Your PSU instead tripped its short circuit protection and shut down which is what should happen.

Any exposed power line touching the case will cause a short to ground. Any power line coming in contact with bare metal will cause a spark. Check the wires for insulation damage or exposed wiring.
An exposed motherboard trace carrying power or a mosfet lead touching the case will cause a short. This is why we have motherboard standoffs. They should be checked.
Plugging in things while the system is on will cause a spark although you probably won't see it.
Loose/damaged connections or wires inside a Molex connector can cause a short. Check the wires going into the connection to see they are secure and can't be pulled out and check the inside of the connection for damage.

 

[Dartmouth]

The PSU has PLENTY of voltage to cause a spark. And that is exactly what happened. Ever seen a car battery short? It's 12V too. A short will cause a large spark and melting of wires and metal if allowed to continue. Your PSU instead tripped its short circuit protection and shut down which is what should happen.

Any exposed power line touching the case will cause a short to ground. Any power line coming in contact with bare metal will cause a spark. Check the wires for insulation damage or exposed wiring.
An exposed motherboard trace carrying power or a mosfet lead touching the case will cause a short. This is why we have motherboard standoffs. They should be checked.
Plugging in things while the system is on will cause a spark although you probably won't see it.
Loose/damaged connections or wires inside a Molex connector can cause a short. Check the wires going into the connection to see they are secure and can't be pulled out and check the inside of the connection for damage.

Okay I did find a small knick on one of the wires for the exhaust fan exposing the copper beneath. Hopefully this is the only problem, but I will check the other cables & standoffs later tonight.

You mention that the inside connections could be damaged. The only damage I can think to look for is burn damage. Is there anything else to keep an eye out for? Also I tried looking up mosfet lead and found only guitar amps and schematics.

 

[Dartmouth]

I checked the other cables and none of the wires would pull out and as far as I could tell there was no burn marks in them nor any exposed wire. I also put in 2 standoffs I had apparently neglected. Going to try it later today.

As an aside why don't these open connections cause any problems like an exposed wire? I'm guessing there is a built-in safety feature.