Physical memory installation

The following figure shows a graphical representation of a system board layout:

This figure shows a two-socket system with a total of 12 memory slots in a triple-channel configuration. Banks and slots are identified by the CPU they are attached to. Slots in a bank are members of a memory channel. The slots are set off-center to more clearly delineate SMP/NUMA nodes. Remember that this is just a sample; manufacturers will use a combination of numbering, lettering, and color-coding.

In order to enable multi-channel memory in the previous example, all slots of any given bank must be filled with DIMMs of the same metric (size and rank). If some slots of a channel are empty, multi-channel is disabled for that group's slots. This will also happen if memory mirroring or a protection scheme that involves disabling slots is enabled. Sparing usually does not disable multi-channel; but if an entire slot is disabled, then the benefits of multi-channel are lost anyway.