HP Kayak XU800 Series, Technical Reference Manual

Page: 42 / 140

42
2 System Board
Memory Controller Hub (8240)
Four-DIMM Memory
Expansion Card
Four DIMM sockets support SDRAM 100 MHz unbuffered ECC memory
modules installed in
pairs . Unused DIMM sockets can be left free.
The MCH supports one Rambus Memory Hub for SDRAM (MRH-S) per
connected channel. Each MRH-S allows bridging of a single SDRAM channel
on to the main Rambus channel. The MRH-S also translates RDRAM and
SDRAM protocols, thus enabling the DIMM Memory Expansion Card to be
used on the Rambus channels.
As only one MRH-S is connected to each channel, the MCH operates the
MRH-S pair in non-interleaved mode.
Models are supplied with 128 MB of SDRAM unbuffered ECC main memory.
Memory upgrades are available in 64 MB, 128 MB, 256 MB or 512 MB
unbuffered 100 MHz ECC SDRAM modules.
MRH-S (Memory Repeater Hub-SDRAM) provides support for two double-
sided 100 MHz SDRAM DIMM sockets.
Each DIMM socket is connected to the SMBus and is described on page 57 .
DIMM SOCKET A0
DIMM SOCKET B0
DIMM SOCKET A1
DIMM SOCKET B1
Memory modules must be
installed in pairs (A0-B0).
I840
Memory
Controller Hub (MCH)
82840-QP
Rambus Channel A
Rambus Channel B
A0 A1
B0 B1
Upgrades are then
installed in pairs
(A1-B1).
MRH-S
MRH-S