Plugged Molex into Motherboard and melted cable

[Lycoth]

Hi everybody,

First of all I want to apologize for asking for technical support, however I know that some of (or most of!) you know a heck of a lot more about this sort of stuff than I do, and i trust you all way more than most technical support / anybody on manufacturer forums.

So I just got a truck load of upgrades for my now heavily outdated computer, and everything was going fine until I powered it on and I had a plume of white smoke and burning. I immediately powered off, unplugged and opened up to have a look and it was obvious what the problem was.

I have the Corsair Carbide 500R. For anybody who doesn't know, It has a Molex cable running down from front I/O panel. At the I/O panel it splits, feeding 2 fans at the front, and then another on the side. In my stupidity, being overwhelmed with desires of a clean looking case, I plugged the molex into the motherboard Chassis fan slot, using an adapter that came with the PSU, instead of running a proper molex cable from the PSU, and it was this molex to the front panel that had melted away completely.

I can only assume that this was caused by plugging it into the Motherboard, as before it was working perfectly fine running from the psu instead.

I removed the front i/o panel, and plugged everything in, booted up, and got into the bios so i'm hoping that the motherboard is fine, unless there is some other kind of damage, thought i would think if it was damaged in this way, it would be much more likely to not even boot. The Graphics card is atleast displaying, but because i have no yet installed an OS, I can't really check anything else. For now i've left it to the side to decide how to approach the situation.

So the question is, Do you think it's likely to have damaged anything else? (Excluding cables that may have been burnt also, i'll have to check them).

Thanks very much guys and gals.

[Photoelectric]

Your next option is to keep going and test the system as it is currently without the front and side fans plugged in, if you're not seeing any damage around the affected fan socket on the motherboard.  I think only the motherboard would have gotten damaged in this case, other than the cable to the front panel and whatever's connected to it. 

P.S.: what motherboard is this and what socket were you plugging the front panel fan cable into?

[Lycoth]

Hi, thanks for your reply.

The Motherboard is Asus Maximus VII Ranger, and I plugged the Molex from the front panel into 4 Pin Chassis fan 1 via adapter. The Adapter looked fine though, no damage to the insulation.

The thing I found unusual is that I would have expected a Chassis fan socket to draw significantly less current than a Molex plugged into a PSU.

[Photoelectric]

Hmm it was probably drawing more power through that socket to power 3 fans than was accounted for in specifications for that fan socket.  Stock Carbide fans?  I don't see info for the front fans, but side fan stats are here:
http://forum.corsair.com/v3/showpost.php?s=731a4bdaf1bedd825b494aa11e3d98ea&p=626388&postcount=4

Anyway, according to corsair:
http://forum.corsair.com/v3/showpost.php?p=532859&postcount=9

"The fan controller can connect up to 3 fans and please make sure to connect the molex connector directly to your power supply to power up the controller"

So it sounds like they know that the resulting power draw is going to be too high for a single motherboard fan socket.

[Lycoth]

Thanks for that. Yeah stock fans at the moment. There is no visible damage on the socket. Only the melted cable. Is it possible that because the Motherboard could not supply the correct amount of power, it ended up drawing more volts or current to compensate, thus resulting in the melted cable? It must have been getting too much of something in order for it to become so badly damaged.

Right now i'm just glad that I can atleast get into Bios. For now that seems like a small victory, with the Motherboard not being completely fudged.

[vun]

I plugged a molex into the mobo while my PC was running once. Kept me from fiddling about inside a PC for quite some time.

[Lycoth]

I plugged a molex into the mobo while my PC was running once. Kept me from fiddling about inside a PC for quite some time.

Oh gosh, I can imagine. I must admit, I was a little shaken up at first. This is the first time i've really screwed up, and having just bought a large amount of upgrades, I was pretty worried about my wallet!

I've just ordered my replacement Panel which was fortunately only £15, so if nothing else is broken i'll be thankful for getting off so lightly.

I'm annoyed at myself though. I'm fairly confident with PC's, and when i'm not sure about something I always google it to make sure I don't screw up. I think because it was related to the same case i'd been using for a couple of years I just didn't think that it could cause an issue.

[Photoelectric]

Is it possible that because the Motherboard could not supply the correct amount of power, it ended up drawing more volts or current to compensate, thus resulting in the melted cable? It must have been getting too much of something in order for it to become so badly damaged.

That's my best guess for what happened.

[tp4tissue]

could you take a picture of   what  was connected to what?

I don't see how it could've melted...  if the  adapter you used  connected correctly to right rail.

[Photoelectric]

could you take a picture of   what  was connected to what?

I don't see how it could've melted...  if the  adapter you used  connected correctly to right rail.

He didn't connect it to the power supply--he plugged the adapter into the motherboard.

[tp4tissue]

could you take a picture of   what  was connected to what?

I don't see how it could've melted...  if the  adapter you used  connected correctly to right rail.

He didn't connect it to the power supply--he plugged the adapter into the motherboard.

yea but that shouldn't be a problem

if the adapter is pulling out 12v or 5v or ground.. and the pins match.. everything should still work..   no?

Unless it's not DC? but it has to be ... 


lets say starting current/voltage is too high...  so that end becomes a big resistor..  The motherboard just goes...  Wh00t  keep feeding it... don't stopp.... wh00000.. there's no cutoff detection?

[Lycoth]

Hi TP, Thanks for your reply.

Unfortunately I can't take a picture right now, but let me elaborate on just how stupid I was.

I plugged the Molex connector for the Fan Controller + 3 fans, into a Molex - Floppy Disk 4 Pin adapter (Which i've only just realized that's what it is. Doh!), Which I then plugged into the Chassis Fan 1 socket on the Motherboard.

[Photoelectric]

Voltage is one thing, power is another.  A lot of current can result in a lot of heat which can melt wires and connectors that are not meant for that amount of current.

[tp4tissue]

Hi TP, Thanks for your reply.

Unfortunately I can't take a picture right now, but let me elaborate on just how stupid I was.

I plugged the Molex connector for the Fan Controller + 3 fans, into a Molex - Floppy Disk 4 Pin adapter (Which i've only just realized that's what it is. Doh!), Which I then plugged into the Chassis Fan 1 socket on the Motherboard.

ahhhh   I see... well this isn't caused by overload then..

the pins don't match...   if it's a 3pin fan header.. the 12v is in the middle..    on the floppy the 12v is on the bottom..   so if you plugged it in so it fits to 1 side... the 12v from the fan header would go into ground...

Assuming there's a resistor in your fan side circuit to prevent this,  that wire indeed becomes a resistor..


I am however surprised the motherboard decides this is ok.. and kept pushing current through there

[tp4tissue]

But ah... you actually CAN do what you want to do with  the connector you have...

make sure the 12v goes into the 12v and ground goes into ground... then it's fine

you don't actually need the 3rd wire..

[Lycoth]

Judging from what you guys are saying, I think it's starting to make sense.

As you said, the 12 volt would be going to ground however, It's a 4 pin Fan header, not 3, so this wouldn't be the problem.

But now that you said it's possible to do what I was attempting to do (Kind of, explains why it fits as well considering computer are like Lego nowadays) I just went and had another look. Obviously the Floppy to Molex is 4 pin, with 4 wires, so that would be pushing through 12 Volts correct?

The Molex to the I/O Panel only has 2 wires terminated, Positions 1 and 2, so I believe this is 5 volts.

Does this just seem like it was just caused by me putting 12 volts through a cable only rated for 5?

[tp4tissue]

Judging from what you guys are saying, I think it's starting to make sense.

As you said, the 12 volt would be going to ground however, It's a 4 pin Fan header, not 3, so this wouldn't be the problem.

But now that you said it's possible to do what I was attempting to do (Kind of, explains why it fits as well considering computer are like Lego nowadays) I just went and had another look. Obviously the Floppy to Molex is 4 pin, with 4 wires, so that would be pushing through 12 Volts correct?

The Molex to the I/O Panel only has 2 wires terminated, Positions 1 and 2, so I believe this is 5 volts.

Does this just seem like it was just caused by me putting 12 volts through a cable only rated for 5?

there's no problem with the rating..  this is very low current as far as electricals go..

just match those up..   

Where the nub is on the fan header, the middle is the 12v...  in the picture it's labeled cpu fan power..

[Lycoth]

Okay so as Photoelectric said, It's the same with 4 pin as it is 3 pin? The 12V was fed into Ground, and the wire became a resistor?

[tp4tissue]

Okay so as Photoelectric said, It's the same with 4 pin as it is 3 pin? The 12V was fed into Ground, and the wire became a resistor?

yes that side of the circuit became a resistor, not just the wire..


the pwm pulse is 5v if i remember correctly,  this is new stuff, so IDK if that component actually has enough current to push fans at all..   

depending on which way you put it in previously... the pwm would've went into either the 5v or the 12v ..   which wouldn't cause damage...


it's only the 12v going into ground that probably did most of the mess..


WHICH wire of the 4 burned.. all of them?

[Lycoth]

Okay, Thanks so much for helping me solve that. Definitely won't be doing that again!

In terms of damage, do you think there will be much to be worried about at this point in time? (Aside from the I/O Panel which i've already ordered a replacement of)

[tp4tissue]

Okay, Thanks so much for helping me solve that. Definitely won't be doing that again!

In terms of damage, do you think there will be much to be worried about at this point in time? (Aside from the I/O Panel which i've already ordered a replacement of)

um.. well you HAVE the molex from the  psu.. just plug it in and test it..

LOL..   the fans should be ok.. pretty sure the last time i opened one there was a diode in the circuit.. as long as there are diodes.. things either go straight or stops..

the panel.. um.... hmmm... probably most likely not designed to take a hit.. but.....  i doubt it could do any damage to your psu..   psus are much smarter and tougher these days.

[Lycoth]

Yeah as soon as I get my new panel i'll just run it from the PSU like a normal person.

Not too worried about the fans. As you said, the should be okay, but even if they're not it's a reason to get after market ones!

More the Mobo I was worried about, But as I said, The PSU and the Mobo are atlesat working as I can get into bios pretty happily, so i'll hope for the best!

[Lycoth]

Hi guys,

Just another thanks and an update. Got my replacement panel and (almost) everything seems to be running fine aside from some PSU problems. Not sure if it's related, still got to have a look and try out a bit more but more or less fine!

Thanks!

[tp4tissue]

Hi guys,

Just another thanks and an update. Got my replacement panel and (almost) everything seems to be running fine aside from some PSU problems. Not sure if it's related, still got to have a look and try out a bit more but more or less fine!

Thanks!

what psu problems.. ?

[Lycoth]

what psu problems.. ?

Hey, sorry, I've been on holiday. PSU Problems were probably nothing. The one that concerned me most was, after it had been unplugged from the mains, when turning on it would boot, and reboot before POST. I had never heard of double booting before but apparently it's more or less normal for Asus Mobos. There are ways around it, but it has no detrimental affects, just annoys some people I suppose, but as the only time i'll experience it is if I get a power cut (Which living in a city, is pretty rare), it won't bother me.

The only other thing was when the PSU shuts off it makes a loud sorta, ping / click sorta noise. Hard to explain but sounds like a spring. Apparently there is a switch in the Corsair AX that can make a noise when it's powered off so it might be that, though it doesn't sound how described on Corsair forums. But it comes with a 7 year warrenty and it's working fine so i'm not really too fussed. If it's normal, great, if it dies after a couple of years then that's fine too!