Doubt you need a BIOS update for this. Most likely the modules are either not in the right slots, or they are not perfectly seated in their slots.
The former, for this board, they need to be installed in slots labeled DIMM_A1 DIMM_B1 DIMM_C1. This is basically every other slot, starting by populating the 1st slot at the edge of the board furthest away from the CPU.