The x79 Dark does require memory to be installed in a specific order for the board to properly POST. You need to install your memory in the slots in this order: 1, 3, 5, 7. If installing more memory, you can use any remaining slots but it's recommended to use 2, 4, 6, 8 in that order. Please see the attached image for the proper DIMM order to install your memory modules in.