Molex 6pin into PCI-E 8pin

[Tangstaaa]

So long story short, I was cleaning my computer with compressed air, then I accidentally re-plugged a molex 6pin that was attached to a fan switch (which controls the speed of the case fans) into the PCI-E 8pin of my PSU without realising. I proceeded to turn my computer on when I noticed smoke and sparks coming from below the fan switch and that is when I unplugged the power and realised the molex was plugged wrong. Now my computer can't be turned on, seeking advice before I bring it into the computer shop. There are some charcoal marks below the fan switch on the inside of the case, I'm guessing maybe I've burnt out a capacitor? Many thanks in advance!

PSU: Thermaltake EVO 750W
Case: NZXT Phantom 410

The Molex 6pin came stock with my case, my GPU at the time was plugged correctly in PSU so I don't think there is anything wrong with my GPU? I'm suspecting that I blew something in the case instead (can that lead to my computer not being able to be turned on?)

 

[ksham]

Remove the GPU and hook a monitor to your motherboard. Can you post with that configuration?

 

[boosted1g]

Can you take a picture of this cable and host it?

Reason being is there is no such thing as a 6 pin molex so we need to see what you are referring to in order to understand what you did.