I would reset the PRAM by holding down the command-option-p-r keys while the computer is off then turn it on while holding those keys down. When you hear the startup chime after the 1st time, it is ok to let go.
If that doesn't work, reseat your RAM (unplug your computer then physically take the RAM out of the computer and put it back in). Then after that try known good RAM. If the problem continues, take it in to your applecare specialist before replacing your logic board.