D2779 (TX100 S2)
Technical Manual
21
Features
Main memory
3.2.1
Fitting rules
●
Minimum required for booting the system is one UDIMM (socket DIMM 1A).
●
Therefore, memory boards must be fitted with UDIMMs as follows.
The maximum performance can be achieved in a symmetric dual-channel
configuration. Therefore, both channels have to be populated with the same
amount of memory. The DRAM device technology may vary from one channel
to the other.
If the amount of memory differs between the two channels, the system board
will run in dual-channel asymmetric mode.
Regardless of the mode, all DIMMs will run at the highest common frequency
that is allowed by the SPD data of the DIMMs and the maximum speed of the
selected configuration.
Configuration 1: single-channel configuration
Configuration 2:
The dual-channel mode is only activated, if the size of the used memory module
in socket DIMM 1B is equal to the summary of the memory modules in the
sockets DIMM 1A and DIMM 2A
(e.g. DIMM 1A = 1GB, DIMM 2A = 1GB, DIMM 1B = 2GB).
Configuration 3 and 4:
For dual-channel configuration arrange identical memory modules in pairs of
the sockets.
Mode
Configuration DIMM 1A
black
DIMM 2A
blue
DIMM 1B
black
DIMM 2B
blue
Single-
channel
1
populated
- -
- -
- -
Single-
/dual-
channel
2
populated populated
populated
- -
Dual-
channel
3
populated
- -
populated
- -
Dual-
channel
4
populated populated populated
populated
Table 1: Configuration of the main memory
