getting somewhere ,as I said earlier remove the graphic card ,and set the bios to safe defaults it should load the os no problem ,you can delve into what to do about the graphics later ,but the card you have is not compatible with crossfire on that board (to the best of my knowledge) you need a 5450 chipped card with crossfire and direct x 11 certified . if your board is configured for crossfire , that could be your problem .
gigabyte mainboards are usually easy to set up ,the trick is in knowing your way around the bios settings ,if you get problems like this its often a good idea to start install with minimal hardware installed .