Datasheet

Intel
®
Xeon
®
Processor 5600 Series Datasheet Volume 2 63
Functional Description
3.7 2X Refresh
The Intel Xeon processor 5600 series supports 2X refresh via two mechanisms. The
traditional software-based mechanism (via MC_CLOSED_LOOP register) supported on
Intel Xeon processor 5500 series, and a new hardware-based mechanism (via
DDR_THERM2# pin).
1. SW Based - when MC_CLOSED_LOOP.REF_2X_NOW configuration bit is set.
2. HW Based - when DDR_THERM2# pin is asserted and its corresponding
MC_DDR_THERM1_COMMANDX.REF_2X register bit is set. Refer to the latest EMTS
for details on the DDR_THERM# and DDR_THERM2#pins.
3.8 Pre-charge Power-Down Slow Exit
Pre-charge Power-Down Slow Exit (PPDS) is a feature of the Intel Xeon processor 5600
series which provides DIMM power savings with a small latency tradeoff. In general,
PPDS is expected to be more beneficial for slower DIMM speeds (800, 1066), and the
power benefit of PPDS is expected to be more significant for larger DIMMs (36 or 72
devices). System developers are encouraged to characterize their overall system power
vs performance under various configurations of interest when deciding to enable PPDS.
The default setting is PPDS disabled. The feature can be enabled by programming the
DIMM to perform slow exit, and setting the tXP value in
MC_CHANNEL_0/1/1_CKE_TIMING_B register appropriately.
Note that PPDS is only supported in 1DPC configurations due to complexities which
arise when a powered down DIMM must terminate an access to another DIMM.
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