Flashing light after memory upgrade?

There is a strange blue flashing led light I see inside the system. I'm not sure if it's IO board or what not but this only occurs when I put 12GB DDR3 1600Mhz memory in the slot?

When I put the old 6GB DDR3 memory that came with the Alienware system, there is no flashing light. Can anyone tell me how to stop it or what's causing this?

Thanks!

Here's the pic of what I'm talking about.

http://imageshack.us/f/812/002sqg.jpg