Intel 4 620 JM80547PG0722MM Data Sheet

87

 lists the Intel Pentium 4 processors in this document that support Enhanced Halt 

Powerdown. 

The Enhanced HALT Powerdown state is configured and enabled via the BIOS. The Enhanced 
HALT state is a lower power state as compared to the Stop Grant State. If Enhanced HALT is not 
enabled, the default Powerdown state entered will be HALT. Refer to the following sections for 
details about the HALT and Enhanced HALT states.

HALT is a low power state entered when all the logical processors have executed the HALT or 
MWAIT instructions. When one of the logical processors executes the HALT instruction, that 
logical processor is halted; however, the other processor continues normal operation. The processor 
will transition to the Normal state upon the occurrence of SMI#, BINIT#, INIT#, or LINT[1:0] 
(NMI, INTR). RESET# causes the processor to immediately initialize itself.

The return from a System Management Interrupt (SMI) handler can be to either Normal Mode or 
the HALT Power Down state. See the Intel Architecture Software Developer's Manual, Volume III: 
System Programmer's Guide for more information.

The system can generate a STPCLK# while the processor is in the HALT Power Down state. When 
the system deasserts the STPCLK# interrupt, the processor will return execution to the HALT state.

While in HALT Power Down state, the processor will process bus snoops.

1.

Refer to the Intel

 4 Processor on 90 nm Process Specification Update for a complete

list of the processor steppings and frequencies that support this feature.

Extreme Edition

Yes

2

2.

This feature is enabled for Pentium 4 Extreme Edition but there will be no thermal benefits if the
feature is used.

670/672

Yes

660/662

Yes

650

Yes

640

Yes

630

Yes