PSU shorting on CPU or mobo?

[userqtyx1]

My mobo has 8 pin ATX12v, my PSU has 4+4 EPS12v. I've read multiple places that they go just fine together, but mine is shorting out (I just built it so not a usage problem)

The PSU works fine on its own with the paperclip test, and when plugged into the GPU and/or the molex for fan control. But whenever I plug either one or both of the 4pins into the mobo, it stops working completely and the EPS12v cable is hot even if I only leave it on for a second to see if it works.

what do I do?

Important specs:
EVGA Supernova 750w PSU, 80+ bronze
ASRock Z97 Extreme4
i5-4690

 

[userqtyx1]

I forgot to add--when the EPS12v is not connected, but everything else is, and I turn on the machine, it works for a few seconds and turns off. Not sure if this is because the CPU is not connected or if the mobo is bad.

 

[userqtyx1]

I really need a solution to this so I can return components if needed.