12th Generation Intel® Core™ Processors

Datasheet, Volume 1 of 2

ID 655258
Date 08/08/2022
Document Table of Contents

System Memory Controller Organization Mode (DDR4/5 Only)

The IMC supports two memory organization modes, single-channel and dual-channel. Depending upon how the DDR Schema and DIMM Modules are populated in each memory channel, a number of different configurations can exist.

Single-Channel Mode

In this mode, all memory cycles are directed to a single channel. Single-Channel mode is used when either the Channel A or Channel B DIMM connectors are populated in any order, but not both.

Dual-Channel Mode – Intel® Flex Memory Technology Mode

The IMC supports Intel Flex Memory Technology Mode. Memory is divided into a symmetric and asymmetric zone. The symmetric zone starts at the lowest address in each channel and is contiguous until the asymmetric zone begins or until the top address of the channel with the smaller capacity is reached. In this mode, the system runs with one zone of dual-channel mode and one zone of single-channel mode, simultaneously, across the whole memory array.

Note:Channels A and B can be mapped for physical channel 0 and 1 respectively or vice versa; however, channel A size should be greater or equal to channel B size.

Intel® DDR4/5 Flex Memory Technology Operations

Dual-Channel Symmetric Mode (Interleaved Mode)

Dual-Channel Symmetric mode, also known as interleaved mode, provides maximum performance on real world applications. Addresses are ping-ponged between the channels after each cache line (64-byte boundary). If there are two requests, and the second request is to an address on the opposite channel from the first, that request can be sent before data from the first request has returned. If two consecutive cache lines are requested, both may be retrieved simultaneously, since they are ensured to be on opposite channels. Use Dual-Channel Symmetric mode when both Channel A and Channel B DIMM connectors are populated in any order, with the total amount of memory in each channel being the same.

When both channels are populated with the same memory capacity and the boundary between the dual channel zone and the single channel zone is the top of memory, IMC operates completely in Dual-Channel Symmetric mode.

Notes:
  • The DRAM device technology and width may vary from one channel to another.
  • Different memory size between channels are relevant to DDR4 and DDR5 only.