RHEL6.7 grub won't boot up after install on Dell R730XD

Brand new install of RHEL6.7 on Dell R730XD w/ PERC H730P raid1 disk using BIOS mode. Installation using kickstart thru PXE boot worked fine, but after the install, the system will not boot up. Always hang before grub even kicked in. Last message was "Booting from Hard drive C:" and it stopped and hang.

Tried to install RHEL7.1 the same way, and everything works and the system boot up fine after install. Same BIOS setup on both. Without changing any BIOS setup, I tried it again w/ rhel6.7, same problem. After the installation is done, system will not boot.

Tried to do boot up in rescue mode using kickstart, then reinstall grub, reboot. same problem.

Anyone has seen this issue?