Gigabyte z87 HD3 Infinite restart loop

My friend just bought a new CPU, Motherboard and RAM.

When we bench tested the system, by shorting the power pins on the front panel header, we found out it goes into an infinite restart loop, It powers on for about one second and then it shuts down again. There was no video output.

We have already tried working ram modules. in all the available slots. Also we tried using another working PSU. (Corsair TX 750W)
We plugged in the CPU fan just to be sure and tried clearing CMOS.

List of components:
Intel Core i5 4670K
Gigabyte GA-Z87-HD3
Crucial Ballistix Tactical BLT2C4G3D1608ET3LX0CEU
Corsair Gs 800

Thanks in advance.

reseat the cpu.

check for any bended pins in the cpu socket area on the board.

i dont know how you tested this, but i would suggest to lay the board on its carton box to to test.

Is there a cooler on the CPU for the test because even for the 1 second with out a cooler it will reach 95+C and shut down for safety. 

Okay, we'll reseat the cpu and check the pins, we tested it on top of the motherboard box. 

We checked the socket and it looks fine, then we reinstalled the cpu and cooler. It did the exact same thing.
We're sending the Motherboard back, i hope it will work with the next one. 

yeah probably dead board then

The new motherboard works fine! Thanks for your help.

Thats good news ☺