Well I've gotten a lot of mixed answers on this question some saying it will be perfectly fine others saying I'm toast.

I was tuning up and adjusting some wires in my computer the other day when this happened:

I connected all my case fans to a cord coming from my psu that had 4 molex connectors, on the other side was a 4-pin sys fan connectors.

My fans had been running fine without them being attached to the motherboard but curious me decided I would connect it anyways only the it was a 4-pin and my motherboard was a 3-pin.

I did some research and a majority of the people said I should be fine. So I went for it.

I plugged the in the 4-pin to the 3-pin and flipped on the power. I heard a faint crackle and immediately cut the power. Very quickly, I'd be surprised if the power was on for much more than half a second.

I smelt for a brief moment the smell of overheated (possible burnt) computer coming from the 4-pin/3-pin contraption. No smoke. And no signs of burning, blackness, anything.

I panicked like I never thought possible. I've yet to explore the back of the motherboard to see if there is any damage there but SOMETHING tells me there wouldn't be. But obviously I can't be sure unless I look.

I few minutes later I plugged it in and turned on the computer, all the lights came on, no beeps, and I GOT a display just like I've always got.

I went into the BIOS and took a look at everything and it at looked good.

Despite this I'm still very worried that there are underlying problems, maybe not with the CPU, GPU, RAM, but maybe with the PSU, or especially the Motherboard.

People have said that if my motherboard or PSU was damaged then nothing would turn on and that I'm okay since everything TURNS on.

Others have said it works but I'm on borrowed time and the life of my computer has been cut drastically.

And others have said that I'm totally skrewed and I need to go and buy new stuff.

What do you think? Please help, this whole situation has got me so worried and caused me more stress than you can imagine 



My OS loads fine. (Linux)
Switching power supplies protect a lot from crowbarring by miswiring. I'd say the noise likely came from your PSU when it was geting crowbarred. Are you sure you didnt hear a clicking noise vs snap-crackle-pop? I say run your system as normal, dont attempt this again, and if you run into further issues later on post back here ( from another computer that works) and we will help you get back up and running or at LEAST diagnose the location of a failure.

The only way I can think of frying a motherboard would be if you were to pass 12V onto the 5V or lower voltage circuitry. The 3 pin config is +12, ground, and tach ( fan speed ). The molex with 4 pins was probably only using 2 or 3 of the 4 pins. 2 if a fan only without tach, and 3 if with tach. Never seen any fans with 4 wires yet.

If the fan was powered reverse the snap-crackle-pop could have been from a fan. The fans are brushless and have a small circuit board to drive the fans through pulsed induction to a fixed magnet vs brushed drive. Some of these have electrolytic capacitors which dont like reverse polarity and tend to snap-crackle-pop and/or explode if powered reverse, although they are very small in size so no big explosion, just a popcorn loud pop. They usually smell pretty good too when they rupture or pop. Sometimes like fish oil. You can smell the fans to see if you can find one that smells fishy..lol... or like cooked electronics. The trace for 12volts running through the main boards are usually pretty rugged, and the ground plane is even more rugged than that to resist burning up. Plus the powersupplies have the anti-crowbar when overloaded and make a tick noise.

Quote

Short-circuit Protection
An output short circuit is defined as any output impedance of less than 0.1 ohms. The
power supply shall shut down and LATCH off for shorting the +3.3 VDC, +5 VDC, or
+12 VDC rails to return or any other rail. The +12 V1DC and +12V2DC should have
separate short circuit and overload protection. Shorts between main output rails and +5
VSB shall not cause any damage to the power supply. The power supply shall either shut
down and latch off or fold back for shorting the negative rails. +5 VSB must be capable of
being shorted indefinitely, but when the short is removed, the power supply shall recover
automatically or by cycling PS_ON#. The power supply shall be capable of withstanding a
continuous short-circuit to the output without damage or overstress to the unit (for
example, to components, PCB traces, connectors) under the input conditions specified in
Section 3.1. The maximum short-circuit energy in any output shall not exceed 240 VA, per
IEC 60950 requirements.

Never seen any fans with 4 wires yet.