HP 9000 rp8420 Server - User Service Guide, Fifth Edition

Figure 1-6 Memory Subsystem
PDH Riser Board
The HP 9000 rp8420 server PDH riser board is a small card that plugs into the cell board at a
right angle. The PDH riser interface contains a microprocessor memory interface microcircuit,
hardware including the processor-dependant code (PDC) flash memory, and a manageability
microcontroller with associated circuitry. The PDH obtains cell board configuration information
from cell board signals and from the cell board local power module (LPM).
Central Processor Units
The cell board will hold up to eight CPUs and is populated with CPUs in increments of two after
meeting the minimum of two CPUs installed on the cell board. Each CPU socket designated in
Figure 1-7 as CPU 0, CPU 1, and so on contains two CPUs since there are two CPUs per processor
module socket. On a cell board, the processors must be the same type and speed. For a partition,
the processors must be the same type and speed. See Table 1-1 for the CPU load order that must
be maintained when adding a processor module socket to the cell board. See Figure 1-7 for the
locations on the cell board for installing processor module sockets.
Table 1-1 Cell Board CPU Load Order
CPU 0 LocationCPU 1 LocationCPU 3 LocationCPU 2 LocationNumber of
CPUs Installed
CPUs installedEmpty slotEmpty slotTerminator installedTwo
CPUs installedEmpty slotEmpty slotCPUs installedFour
Detailed HP 9000 rp8420 server Description 25