Another Quote from AMD's k10 dev guide
2.6 The Northbridge (NB)
Each processor includes a single Northbridge that provides the interface to the local CPU core(s), the interface to system memory, the interface to other processors, and the interface to system IO devices. The NB includes all power planes except VDD; see section 2.4.1 [Processor Power Planes And Voltage Control] on page 25 for more information.
The NB of each node is responsible for routing transactions sourced from CPU cores and links to the appropriate CPU core, cache, DRAM, or link. See section 2.9.3 [Access Type Determination] on page 107 for more information.

2.6.1 Northbridge (NB) Architecture

Major NB blocks are: System Request Interface (SRI), Memory Controller (MCT), DRAM Controllers (DCTs), L3 cache, and Cross Bar (XBAR). SRI interfaces with the CPU core(s). MCT maintains cache coherency and interfaces with the DCTs; MCT maintains a queue of incoming requests called MCQ. XBAR is a switch that routes packets between SRI, MCT, and the links.
The MCT operates on physical addresses. Before passing transactions to the DCTs, the MCT converts physical addresses into normalized addresses that correspond to the values programmed into [The DRAM CS Base Address Registers] F2x[1, 0][5C:40]. Normalized addresses include only address bits within the DCTs’ range.
The normalized address varies based on DCT interleave and hoisting settings in [The DRAM Controller Select Low Register] F2x110 and [The DRAM Controller Select High Register] F2x114 as well as node interleaving based on [The DRAM Base/Limit Registers] F1x[1, 0][7C:40].
Code:
Core 0 ----
           |
Core 1 ----                 
           |---- SRI ---- XBAR ---- cHT
Core 2 ----                 |
           |               MCT --- L3
Core 3 ----                 |
                           ---
                          |   |
                        DCT0 DCT1
                          |   |
                      LDIMM0 LDIMM1
So SRI, XBAR, MCT, L3 DCT0 and DCT1 all run on NB speed?
Or do the DCT's run on ram clock?