@TrickStar, I'm in exactly the same boat as you and can't find a way to PXE boot UEFI. I've done an in place upgrade from windows server 2008 to server 2012 but PXE boot still doesn't work with UEFI clients. Booting from UEFI media (USB Flash Drive) is working fine. I may need to install a fresh Windows 2012 server to see if that changes anything.