Intel SR1680MV ユーザーズマニュアル

19

System Memory Channel Population Requirements for 

Memory RAS Modes

The rules on channel population and channel matching vary by the RAS mode used. There 

are three different memory RAS modes: Independent Channel Mode, Mirrored Channel 

Mode, and Lockstep Channel Mode.

Independent Channel Mode

Channels can be populated in any order in this mode. All these channels may be populated 

in any order and have no matching requirements. All channels must run at the same 

interface frequency but individual channels may run at different DIMM timings (RAS 

latency, CAS latency, and so forth).

Mirrored Channel Mode

In Mirrored Channel Mode, the memory contents are mirrored between Channel 0 and 

Channel 1. As a result of the mirroring, the total physical memory available to the system 

is half of what is populated. Mirrored Channel Mode requires that Channel 0 and Channel 

1 must be populated identically with regards to size and organization. DIMM slot 

populations within a channel do not have to be identical but the same DIMM slot location 

across Channel 0 and Channel 1 must be populated the same. Channel 2 is unused in 

Mirrored Channel Mode.

Lockstep Channel Mode

In Lockstep Channel Mode, each memory access is a 128-bit data access that spans 

Channel 0 and Channel 1. Lockstep Channel mode is the only RAS mode that supports x8 

SDDC. Lockstep Channel Mode requires that Channel 0 and Channel 1 must be populated 

identically with regards to size and organization. DIMM slot populations within a channel 

do not have to be identical but the same DIMM slot location across Channel 0 and 

Channel 1 must be populated the same. Channel 2 is unused in Lockstep Channel Mode.

For your reference, Table 3 offers an ideal DIMM population option for A-F channels of 

processor 1 and 2. The last column in tables marks DIMM installation under Mirrored 

Channel Mode for your reference.