Specification Sheet

Datasheet, Volume 1 of 2 75
Power Management
4.3.2.3 Dynamic Power-Down
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 precharge power-down (CKE de-assertion
with all pages closed). Precharge 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 refresh.
4.3.2.4 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, and any DLL circuitry
related ONLY to unused signals 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).
4.3.3 DDR Electrical Power Gating (EPG)
The DDR I/O of the processor supports Electrical Power Gating (DDR-EPG) while the
processor is at C3 or deeper power state.
In C3 or deeper power state, the processor internally gates VDDQ for the majority of
the logic to reduce idle power while keeping all critical DDR pins such as CKE and VREF
in the appropriate state.
In C7 or deeper power state, the processor internally gates V
CCIO
for all non-critical
state to reduce idle power.
In S3 or C-state transitions, the DDR does not go through training mode and will
restore the previous training information.
4.3.4 Power Training
BIOS MRC performing Power Training steps to reduce DDR I/O power while keeping
reasonable operational margins, still ensuring platform operation. The algorithms
attempt to weaken ODT, driver strength and the related buffers parameters both on the
MC and the DRAM side and find the best possible trade-off between the total I/O power
and the operational margins using advanced mathematical models.
S3 Self-Refresh Mode Self-Refresh Mode
S4 Memory power-down (contents lost) Memory power-down (contents lost)
Table 4-8. Targeted Memory State Conditions (Sheet 2 of 2)
State Memory State with Processor Graphics Memory State with External Graphics