12th Generation Intel® Core™ Processors Datasheet, Volume 1 of 2
Dynamic power-down of memory is employed during normal operation. Based on idle conditions, a given memory rank may be powered down. The IMC implements aggressive CKE control to dynamically put the DRAM devices in a power-down state.
The processor IA core controller can be configured to put the devices in active power down (CKE de-assertion with open pages) or pre-charge power-down (CKE de-assertion with all pages closed). Pre-charge power-down provides greater power savings but has a bigger performance impact, since all pages will first be closed before putting the devices in power-down mode.
If dynamic power-down is enabled, all ranks are powered up before doing a refresh cycle and all ranks are powered down at the end of the refresh.