I dug around on Intel's site and looked at the beep codes/light flash codes for you board.
Sounds like a memory problem to me. I had a similar issue with a PC I built a few years ago. Turns out the memory was incompatible because my motherboard was so incredibly picky. Intel boards can be like that...
Any way you can try a different stick of DDR3? If worse comes to worse just pick one up at BBY, install it, and return it once you've figured out the problem.
Have you tried just installing one stick at a time? In different slots?