I had similar trouble with the last board i purchased and only had one stick of ram available.  If the computer wouldn't boot, I would just shut down the power supply, pull the ram and reset it in the other socket and it would boot (no idea why).  While testing for best overclock, if the miner crashed then it wouldn't boot until swapping ram slots yet again.   I have other boards running with only one stick, so I am not sure what is going on. I am using the board, and it has been hashing for 6 weeks no problems.  Good luck.