3-4 www.hp.com Technical Reference Guide
Processor/Memory Subsystem
3.3.1 Memory Loading/Upgrading
Table 3-2 shows suggested memory configurations for these systems.
CAUTION: Always power down the system and disconnect the power cord from the AC outlet before
adding or replacing memory modules. Changing memory modules while the unit is plugged into an
active AC outlet could result in equipment damage.
✎
Table 3-2 does not list all possible configurations.
✎
If only one DIMM is installed, it MUST be installed in socket 4.
HP recommends using dual-channel loading (symmetrical, same-capacity, same-speed modules
across both channels) to achieve the best performance. The system automatically selects single-
or dual-channel operation depending on how DIMMs are installed. For dual-channel operation,
the loading priority is to populate socket XMM4 before XMM2 for channel B, and socket
XMM3 before XMM1 for channel A.
✎
Memory amounts over 3 GB may not be fully accessible with 32-bit operating systems due to
system resource requirements. Addressing memory above 4 GB requires a 64-bit operating
system.
3.3.2 Memory Mapping and Pre-allocation
Figure 3-2 shows the system memory map. The RS780C North Bridge pre-allocates a portion of
system memory for video use (refer to chapter 6). Pre-allocated memory is not available to the
operating system. The amount of system memory reported by the OS will be the total amount
installed less
the pre-allocated amount.
Table 3-2.
Memory Socket Loading
Channel A Channel B
Socket
XMM 1
Socket
XMM 3
Socket
XMM 2
Socket
XMM 4 Total
none none none 512 MB 512 MB (single channel loading)
none 512 MB none 512 MB 1 GB (dual-channel loading)
none none none 1 GB 1 GB (single chanel loading)
none 1 GB none 1 GB 2 GB (dual-channel loading)
1 GB 1 GB 1 GB 1 GB 4 GB (dual-channel loading)
none 2 GB none 2 GB 4 GB (dual-channel loading)
2 GB 2 GB 2 GB 2 GB 8 GB (dual-channel loading)
