Intel Pentium 4 Processor In the 423-pin Package Thermal Design Guidelines

Pentium® 4 processor in the 423-pin package Thermal Design Guidelines
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Figure 13. Processor Performance versus System Cooling Capability
8.4.1 Operating System & Application Software Considerations
The Thermal Monitor feature and its thermal control circuit works seamlessly with any ACPI compliant operating
system. The Thermal Monitor feature is transparent to application software since the processor bus snooping, ACPI
timer and interrupts are active at all times.
8.4.1.1 Operating System Support
Activation of the thermal control circuit during a non-ACPI aware operating system boot process may result in
incorrect calibration of operating system software timing loops. The BIOS must disable the thermal control circuit
prior to boot and then the operating system or BIOS must enable the thermal control circuit after the operating
system boot process completes. Refer to the IA32 Intel Architecture Software Developer Manuals for specific
programming details.
Intel is working with the major operating system vendors to ensure support for non-execution based operating
system calibration loops and ACPI support for the Thermal Monitor feature. Per Microsoft, Microsoft* Windows*
98ES and Windows 2000 use non-execution based calibration loops and therefore have no issues with the Thermal
Monitor feature. When installing Windows NT* 4.0, the user must ensure the APIC-based HAL is used. It is
expected that other OS solutions (Linux*, Unix*, etc) will provide updates to ensure compatibility.
8.5 Legacy Thermal Management Capabilities
In addition to Thermal Monitor, the Pentium® 4 processor supports the same thermal management features as
available on the Intel Pentium III processor. These features are the on-die thermal diode and THERMTRIP# signal
for indicating catastrophic thermal failure.
8.5.1 Thermal Diode
The Pentium 4 processor incorporates an on-die thermal diode, which can be used with an external device (thermal
diode sensor) to monitor long-term temperature trends. By averaging this data over long time periods (hours/days vs.
min/sec), it may be possible to derive a trend of the processor temperature. Analysis of this information could be
useful in detecting changes in the system environment that may require attention. Design characteristics and usage
Chassis Cooling Capacity
Processor
Performance
Application/benchmark
maximum
Sporadic
activation
Thermal control
circuit regularly
active
EMTS
Max Power
Max
70%
NOT TO SCALE
No activation
expected