HP Dc7800 Hardware Reference Guide - HP Compaq dc7800 Convertible Minitower - Page 23

Populating DIMM Sockets, labeled XMM1, XMM2

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Populating DIMM Sockets There are four DIMM sockets on the system board, with two sockets per channel. The sockets are labeled XMM1, XMM2, XMM3, and XMM4. Sockets XMM1 and XMM2 operate in memory channel A. Sockets XMM3 and XMM4 operate in memory channel B. Figure 2-7 DIMM Socket Locations Table 2-1 DIMM Socket Locations Item Description Socket Color 1 DIMM socket XMM1, Channel A Black 2 DIMM socket XMM2, Channel A White 3 DIMM socket XMM3, Channel B White 4 DIMM socket XMM4, Channel B White NOTE: A DIMM must occupy the black DIMM1 socket. Otherwise, the system will display a POST error message indicating that a memory module must be installed in the black socket. The system will automatically operate in single channel mode, dual channel mode, or flex mode, depending on how the DIMMs are installed. ● The system will operate in single channel mode if the DIMM sockets are populated in one channel only. ● The system will operate in a higher-performing dual channel mode if the total memory capacity of the DIMMs in Channel A is equal to the total memory capacity of the DIMMs in Channel B. The technology and device width can vary between the channels. For example, if Channel A is populated with two 512MB DIMMs and Channel B is populated with one 1GB DIMM, the system will operate in dual channel mode. ● The system will operate in flex mode if the total memory capacity of the DIMMs in Channel A is not equal to the total memory capacity of the DIMMs in Channel B. In flex mode, the channel populated with the least amount of memory describes the total amount of memory assigned to dual channel and the remainder is assigned to single channel. For optimal speed, the channels should be balanced so that the largest amount of memory is spread between the two channels. If one channel will have more memory than the other, the larger amount should be assigned to Channel A. For example, if you are populating the sockets with one 1GB DIMM, and three 512MB DIMMs, Channel ENWW Installing Additional Memory 17

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Populating DIMM Sockets
There are four DIMM sockets on the system board, with two sockets per channel. The sockets are
labeled XMM1, XMM2, XMM3, and XMM4. Sockets XMM1 and XMM2 operate in memory channel A.
Sockets XMM3 and XMM4 operate in memory channel B.
Figure 2-7
DIMM Socket Locations
Table 2-1
DIMM Socket Locations
Item
Description
Socket Color
1
DIMM socket XMM1, Channel A
Black
2
DIMM socket XMM2, Channel A
White
3
DIMM socket XMM3, Channel B
White
4
DIMM socket XMM4, Channel B
White
NOTE:
A DIMM must occupy the black DIMM1 socket. Otherwise, the system
will display a POST error message indicating that a memory module must be
installed in the black socket.
The system will automatically operate in single channel mode, dual channel mode, or flex mode,
depending on how the DIMMs are installed.
●
The system will operate in single channel mode if the DIMM sockets are populated in one channel
only.
●
The system will operate in a higher-performing dual channel mode if the total memory capacity of
the DIMMs in Channel A is equal to the total memory capacity of the DIMMs in Channel B. The
technology and device width can vary between the channels. For example, if Channel A is
populated with two 512MB DIMMs and Channel B is populated with one 1GB DIMM, the system
will operate in dual channel mode.
●
The system will operate in flex mode if the total memory capacity of the DIMMs in Channel A is not
equal to the total memory capacity of the DIMMs in Channel B. In flex mode, the channel populated
with the least amount of memory describes the total amount of memory assigned to dual channel
and the remainder is assigned to single channel. For optimal speed, the channels should be
balanced so that the largest amount of memory is spread between the two channels. If one channel
will have more memory than the other, the larger amount should be assigned to Channel A. For
example, if you are populating the sockets with one 1GB DIMM, and three 512MB DIMMs, Channel
ENWW
Installing Additional Memory
17