I have a h81 btc board and three Gigabyte r9 270. I am using unpowered risers and the molex are connected to Themen board.
However, in bamt aswell as Win 8.1 my rig only detects 2 gpus. All gpus are definetely ok as I have tested them in other rigs.
Have you any Idea what is going on? Ps. I have already done a BIOS update
Can we see some pics