Seems there're some conflicts between Matrix RAID OROM and your video card.
First of all, do you mean Radeon HD 6450? This card is not validated on this board, so I won't be able to give you a solid answer. Just several general suggestions:
1. Update BIOS/Firmware to latest version if you haven't done so
2. Go to BIOS => Advanced => PCI Configuration. Change the settings of "Maximize Memory below 4GB" and "Memory Mapped I/O above 4GB"
3. Does the ESRT2 ROM work with this video card?
4. Try a different video card.