Intel PentiumD 950 HH80553PG0964M Manuel D’Utilisation
Codes de produits
HH80553PG0964M
Features
94
Datasheet
6.2.4
Enhanced HALT Snoop or HALT Snoop State,
Stop Grant Snoop State
The Enhanced HALT Snoop State is used in conjunction with the new Enhanced HALT
state. If Enhanced HALT state is not enabled in the BIOS, the default Snoop State
entered will be the HALT Snoop State. Refer to the following sections for details on
HALT Snoop State, Grant Snoop State and Enhanced HALT Snoop State.
6.2.4.1
HALT Snoop State, Stop Grant Snoop State
The processor will respond to snoop transactions on the FSB while in Stop-Grant state
or in HALT Power Down state. During a snoop transaction, the processor enters the
HALT Snoop State:Stop Grant Snoop state. The processor will stay in this state until the
snoop on the FSB has been serviced (whether by the processor or another agent on the
FSB). After the snoop is serviced, the processor will return to the Stop Grant state or
HALT Power Down state, as appropriate.
6.2.4.2
Enhanced HALT Snoop State
The Enhanced HALT Snoop State is the default Snoop State when the Enhanced HALT
state is enabled via the BIOS. The processor will remain in the lower bus ratio and VID
operating point of the Enhanced HALT state.
While in the Enhanced HALT Snoop State, snoops are handled the same way as in the
While in the Enhanced HALT Snoop State, snoops are handled the same way as in the
HALT Snoop State. After the snoop is serviced the processor will return to the Enhanced
HALT state.
6.2.5
Enhanced Intel
®
SpeedStep
®
Technology
Enhanced Intel SpeedStep
®
technology enables the processor to switch between
frequency and voltage points, which may result in platform power savings. To support
this technology, the system must support dynamic VID transitions. Switching between
voltage/frequency states is software controlled.
Note:
Not all processors are capable of supporting Enhanced Intel SpeedStep technology.
More details on which processor frequencies will support this feature will be provided in
future releases of the Intel
®
Pentium
®
D Processor 900 Sequence and Intel
®
Pentium
®
Processor Extreme Edition 955, 965 Specification Update.
Enhanced Intel SpeedStep technology is a technology that creates processor
Enhanced Intel SpeedStep technology is a technology that creates processor
performance states (P states). P states are power consumption and capability states
within the Normal state as shown in
. Enhanced Intel SpeedStep technology
enables real-time dynamic switching between frequency and voltage points. It alters
the performance of the processor by changing the bus to core frequency ratio and
voltage. This allows the processor to run at different core frequencies and voltages to
best serve the performance and power requirements of the processor and system. Note
that the front side bus is not altered; only the internal core frequency is changed. To
run at reduced power consumption, the voltage is altered in step with the bus ratio.
The following are key features of Enhanced Intel SpeedStep technology:
The following are key features of Enhanced Intel SpeedStep technology:
• Voltage/Frequency selection is software controlled by writing to processor MSRs
(Model Specific Registers); thus, eliminating chipset dependency.
• If the target frequency is higher than the current frequency, Vcc is incriminated in
steps (+12.5 mV) by placing a new value on the VID signals and the processor
shifts to the new frequency. Note that the top frequency for the processor can not
be exceeded.
• If the target frequency is lower than the current frequency, the processor shifts to
the new frequency and V
CC
is then decremented in steps (-12.5 mV) by changing
the target VID through the VID signals.
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