Compaq dc7700 Hardware Reference Guide - dc7700 CMT - Page 24

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 Item Description 1 DIMM socket XMM1, Channel A 2 DIMM socket XMM2, Channel A 3 DIMM socket XMM3, Channel B 4 DIMM socket XMM4, Channel B Socket Color Black White White White 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 256MB DIMMs and Channel B is populated with one 512MB 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. For example, if you are populating the sockets with one 1GB DIMM, two 512MB DIMMs, and one 256MB DIMM, one channel should be populated with the 1GB DIMM and one 256MB DIMM and the other channel 18 Chapter 2 Hardware Upgrades ENWW