Pre Nehalem Intel CPUs had a non-integrated memory controller as far as I'm aware and they grabbed the contents of DRAM and placed it on the external data bus to be received by the cpu etc. The CPU used the address bus to communicate with the MCC and tell it what information it wanted but after Nehalem Intel CPUs had a integrated Memory Controller Chips that were in the CPU so what happened to the address bus? I'm guessing that it still exists but directly connects the CPU to the DRAM.