Sounds like your cpu isnt seated right. I would reinstall your cpu, its probally not making good contact with the pins. I have heard this before, with people seeing less ram then they really have. Faulty mem controller? also check to make sure your ram is all the way in the slot. It can be tight fit on a new board. I had a old epox that did that to me, I had to press hard on the dimms to get it to post. Bump up your northbridge voltage a touch, helps with stability.

Could be a bad board too. Memory slots are the #1 rma reason. Did you alternate sticks and slots?