HP ProDesk 400 G7 SFF Maintenance And Service Manual page 34

1.2 V DDR4-SDRAM memory modules
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CAS latency 17 DDR4 2666/3200 MHz (17-17-17 timing)
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Mandatory JEDEC SPD information
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The computer supports the following setups:
512 Mbit, 1 Gbit, 2 Gbit, and 4 Gbit non-ECC memory technologies
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● Single-sided and double-sided memory modules
Memory modules constructed with ×8 and ×16 DDR devices; memory modules constructed with ×4 SDRAM
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are not supported
NOTE: The system does not operate properly if you install unsupported memory modules.
There are four memory 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 automatically operates in single-channel mode, dual-channel mode, or flex mode, depending on
how the DIMMs are installed.
NOTE: Single-channel and unbalanced dual-channel memory configurations results in inferior graphics
performance.
The system operates in single-channel mode if the DIMM sockets are populated in one channel only.
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The system will operate in a higher-performing dual-channel mode if the total memory capacity of the
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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 operates in flex mode if the total memory capacity of the DIMMs in channel A is not equal to
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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 runs 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.
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26 Chapter 4 Removal and replacement procedures ENWW