Unfortunately, when you buy a new motherboard, it may have an old BIOS version.
Did you update BIOS using the BIOS flashback utility (see the motherboard manual section 2.3.10)? If you update the BIOS to the latest release, it will remedy any possible compatibility issue. Then we can troubeshoot from there. All you need is the PSU plugged into the motherboard in order to do this.
Of course you will need to download the latest BIOS release from the ASUS.com site and burn it to a USB stick:http://usa.asus.com/Motherboards/Intel_Socket_1155/P8Z77V_PROTHUNDERBOLT/#download