Plugged PCI-E into ESP/ATX... Something's Broken!

[Grfffn]

Yep. Been there done that, huh?

Was moving an old mobo into a new case and managed to plug an 8pin PCI-E into my CPU's power spot. Brief moment of panic followed along with a click and the smell of smoke! Computer will now turn fans slightly before powering off on startup.

Basically, what I've done is run the PSU, CPU, and motherboard isolated and cannot discover which is actually broken. Is there any sure-fire broken piece with this sort of thing or am I going to have to dig out my voltmeter 😀

Anyways, thanks and I promise, it won'[t happen again 😛

 

[InvalidError]

The row spacing and keying between PCIe and EPS12 connectors is different, it should be physically impossible to plug the wrong one in the wrong place by accident.

The pinout of PCIe and EPS12 is inverted (the GND and 12V pin rows are swapped) so successfully forcing a PCIe connector into the motherboard's EPS12 connector shorts the PSU's 12V rail to ground. Depending on how much short circuit current passed through the wires and motherboard before the PSU shut down, this could have fried the PSU's EPS12 12V wires and the thermal relief around the motherboard's EPS12 GND pins. If the motherboard had reverse voltage protection diodes, those diodes may have shorted out from excess current too.

Those are the two highest probability victims.

 

[Outlander_04]

You can indeed insert a pci-e 8 pin into a motherboards 12 volt EPS socket with a bit of force .

My guess is that the motherboards power circuitry is toasted .
Very unlikely it can be fixed unless you have great access to electronic components and exceptional skills with a soldering iron

 

[Grfffn]

The row spacing and keying between PCIe and EPS12 connectors is different, it should be physically impossible to plug the wrong one in the wrong place by accident.

The pinout of PCIe and EPS12 is inverted (the GND and 12V pin rows are swapped) so successfully forcing a PCIe connector into the motherboard's EPS12 connector shorts the PSU's 12V rail to ground. Depending on how much short circuit current passed through the wires and motherboard before the PSU shut down, this could have fried the PSU's EPS12 12V wires and the thermal relief around the motherboard's EPS12 GND pins. If the motherboard had reverse voltage protection diodes, those diodes may have shorted out from excess current too.

Those are the two highest probability victims.

I dont remember having to really force anything in at all. Regardless, thanks for the massive help. So depending on how much passed through, its possible that both could have shorted out from the current?

 

[InvalidError]

The PSU should be relatively simple to test: if there is an internal short or something blown, you can disconnect all the output wires, "paper clip" the PSU to turn it on (green wire to ground on the ATX connector) and if the PSU stays on, check if you have 12V on all the 12V connections including the PCIe and EPS12 connectors. If there is voltage within specs everywhere, then the PSU is likely still good. In the ATX PSU specs, a PSU is supposed to survive a short from any rail to ground with no damage.

Since you smelled smoke, you should be able to take the PC apart, take your suspected components outdoors to fan the scents off, bring them back in and do a "smell test" to check which component(s) smell worse. If smoke really did come out of something, it will usually leave some obvious visual cues too. For the PSU, you may be able to use a flashlight to illuminate parts of the PCB while you observe through other holes and spot obvious issues that way with a little luck.