New desktop build -- No power up issue

[Venbred]

Hello,
Recently helped a friend with getting parts for his new desktop and help with assembly.
I've assembled dozens of desktops and have never ran into this issue.

First off:
Mobo: Gigabyte GA-z170x-Gaming 7 (rev: 1.0)
GPU: GTX 680 SC
CPU: i-5 6600 LGA1151
RAM: Vengence LPX DDR4 3000MHz (2x8GB)
PSU: Thermaltake Toughpower 750W (W0116RU)

Issue
After assembly when attempting to do the initial boot not much of anything happened. The fans started spinning up including CPU cooler, lights came on and second later nothing and no error code displayed on the mobos onboard error display.
Several more attempts produced a burning smell so we tossed it up to being a defective mobo out of box, it happens and has to me once before.

Well, now the new mobo is in and everything reassembled and same problem with everything spinning up for just a second then nothing. This time we've not smelled anything hot or burning so am now here asking opinions.

I've checked all connections again and again. Everything seems solid and nothing that I've been able to see is grounding out, anyone have any suggestions?

Thanks to any responses!

 

[alexoiu]

Hi, Try testing then board outside the case, only CPU and CPU fan installed, both 24 and 8 pin power cables connected. No other wires/components.
Start the board by shortly touching with a screwdriver the 2 pins on the board corresponding to the case power button.
See if still same issue.