HP Workstation xw6000 Hardware Reference Manual page 5

Each DIMM within a pair should be identical in technology. For example, you cannot mix a 256 MB
9-device DIMM with a 128MB 18-device DIMM on the same channel.
NOTE: To identify which DIMM technology you are using, compare the memory size and number of
DRAM components on the module. A 128 MB DIMM has 18 DRAM components that fully populate both
sides of the module. A 256MB DIMM has 9 DRAM components; four on one side, five on the other.
The first pair of DIMMS should be installed in slots 1 and 2. The DIMM slots are numbered
sequentially. Slot 1 is closest to the CPUs.
The second pair of DIMMS, if any, should be installed in slots 3 and 4.
DIMMs must be installed correctly. Be sure to match the keyed slot on the DIMM with the tab on the
DIMM socket.
For optimal system performance, DIMMs should be installed in identical pairs in the following three
configurations: slot 1 and 2, slot 3 and 4, or all DIMM slots populated in paired format.
If you are using a single DIMM configuration, the DIMM should be installed in slot 1 or slot 3.
NOTE: Although a single-DIMM configuration is possible, it does not provide the optimal system
performance that a dual-DIMM (dual-channel) of matching sizes, configuration provides.
If you are installing two DIMMs of different sizes, they can only be installed in slot 1 and slot 3
with each DIMM occupying either slot.
NOTE: Although a mixed size dual-DIMM configuration is possible, it does not provide the optimal
system performance that a dual-DIMM (dual-channel) of matching sizes, configuration provides.
No other memory configurations are supported. Attempts to install memory in other configurations
will result in unpredictable system performance.
NOTE: The following table provides acceptable pairing configurations but do not cover all module
capacities. However, the same pairing configuration applies regardless of the module type and capacity.
Table 1 - Available Memory Configurations for the xw6000
Module Slot
Total XMM1
2 9-device
2 Empty
2 18-device
2 Empty
4 18-device
4 9-device
NOTE: Modules must be paired as indicated in this table where slots 1 and 2, and slots 3 and 4
must contain like modules.
Channel A
Slot
XMM3
Empty
18-device
Empty
9-device
9-device
18-device
Channel B
Slot Slot
XMM2 XMM4
9-device Empty
Empty 18-device
18-device Empty
Empty 9-device
18-device 9-device
9-device 18-device
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