BIOS works but PC shuts down during installing Windows 8 - New Build

[Allan8]

I have just completed my first PC build and was excited the BIOS was displayed on the monitor from turning the PC on for the very first time. All of the hardware was recognized.

The issue I'm having is installing Windows 8. The farthest I've gotten into the installation is typing the first 5 product keys - then my whole PC shuts down. A second later without touching it, the fans start spinning but only for a second or two until it turns itself off again - it does this repeatedly (turning on and off) until I turn off the power supply or long press the power button.

Please help. I am new to this.

What I've done:
- Manually checked the voltage of the PSU with the multimeter (it was fine)
- Cleared CMOS
- Switched the memorys in different RAM slots
(does the same thing with no improvements)

Anything else I can do?

Reminder: BIOS works (pc stays on for a long period of time - Installing Windows 8 (pc shuts down during installation and repeatedly turns on and off)

Motherboard: Gigabyte Z77X-3DH rev1.0
CPU: i5 3570k
Memory: Kingston HyperX Blu 8GB (2 x 4GB)
Storage: Western Digital Caviar Black 1TB 64M Sata 3
Graphics Card: Gigabyte GTX 760 2GB
PSU: Fractal Design Tesla R2 800W
Case: Bitfenix Ghost
OS: Windows 8 OEM (using optical drive to boot)

Thanks in advance.

 

[ur6beersaway]

The back of the motherboard is shorting out to your case somewhere.

 

[Allan8]

The back of the motherboard is shorting out to your case somewhere.

Do you have any solutions that i could try regarding this problem?
I read somewhere using cardboard washers might work...

 

[ur6beersaway]

Checklist~http://www.tomshardware.com/forum/261145-31-perform-steps-posting-post-boot-video-problems