Nehalem supports only DDR3
 

Intel has revealed to the world that the upcoming Nehalem generation of processors will only support DDR3 memory. As the memory controller is now in the CPU and the Northbridge as we knew it from Intel’s past and present will cease to exist, it won't be that easy to change the memory controller in order to support DDR2.

http://www.fudzilla.com/index.php?op...54&Ite mid=36