12th Generation Intel® Core™ Processors Datasheet, Volume 1 of 2
DRAM I/O Power Management
Unused signals should be disabled to save power and reduce electromagnetic interference. This includes all signals associated with an unused memory channel. Clocks, CKE, ODT, and CS signals are controlled per DIMM rank and will be powered down for unused ranks.
The I/O buffer for an unused signal should be tri-stated (output driver disabled), the input receiver (differential sense-amp) should be disabled. The input path should be gated to prevent spurious results due to noise on the unused signals (typically handled automatically when input receiver is disabled).