x79-ud3 sierra installation

Hey Guys, I am trying to install sierra but got a few issues and was hoping to see if i can get some help.

Motherboard is Gigabyte x79-ud3
Intel Core i7 3930k
16gb of ram
Nvidia GTX 580
using wd hdd just to test out

After making the usb with Unibeast and setting up bios, when i press F12 i just get reboot "insert boot media in selected proper device"

Any Guidance or help would be appreciate it.