I have exactly the same problem. But there are no bent CPU pins.
The PSU will power on, the fans spin for two seconds and the motherboard lights up - then everthing turns off. This only happens when I plug in the 2x 8 pin connectors. I have a modular Corsair AX 1200 and have tried different modules but still the same problem. I have taken out all PCI cards, memory and the CPU with no effect.
Please help