For proper system operation, the DDR3-SDRAM DIMMs must be:
●
industry-standard 240-pin
●
unbuffered non-ECC PC3-8500 DDR3-1066 MHz-compliant or PC3-10600 DDR3-1333 MHz-
compliant
●
1.5 volt DDR3-SDRAM DIMMs
The DDR3-SDRAM DIMMs must also:
●
support CAS latency 7 DDR3 1066 MHz (7-7-7 timing) and CAS latency 9 DDR3 1333 MHz
(9-9-9 timing)
●
contain the mandatory JEDEC SPD information
In addition, the computer supports:
●
512-Mbit, 1-Gbit, and 2-Gbit non-ECC memory technologies
●
single-sided and double-sided DIMMs
●
DIMMs constructed with x8 and x16 DDR devices; DIMMs constructed with x4 SDRAM are not
supported
NOTE:
The system will not operate properly if you install unsupported DIMMs.
Populating DIMM Sockets
There are four DIMM sockets on the system board, with two sockets per channel. The sockets are
labeled DIMM1, DIMM2, DIMM3, and DIMM4. Sockets DIMM1 and DIMM2 operate in memory
channel B. Sockets DIMM3 and DIMM4 operate in memory channel A.
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 1-GB DIMMs and Channel B is populated with one 2-GB 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 2-GB DIMM, and three 1-GB
DIMMs, Channel A should be populated with the 2-GB DIMM and one 1-GB DIMM, and Channel
B should be populated with the other two 1-GB DIMMs. With this configuration, 4-GB will run as
dual channel and 1-GB will run as single channel.
●
In any mode, the maximum operational speed is determined by the slowest DIMM in the system.
42
Chapter 5 Removal and Replacement Procedures
