Cpu Features - TYAN TOMCAT I7221A User Manual

Tomcat i7221A S5151 Chapter 3: BIOS Setup

3.4.1 CPU Features

Press [Enter] to access advanced features of the CPU.
Delay Prior to Thermal
This BIOS feature is only valid for systems that are powered by 0.13µ Intel Pentium 4
processors with 512KB L2 cache.
These processors come with a Thermal Monitor that consists of an on-die thermal sensor and
a Thermal Control Circuit (TCC).
When the Thermal Monitor is in automatic mode and the thermal sensor detects that the
processor has reached its maximum safe operating temperature, it will activate the TCC. The
TCC will then modulate the clock cycles by inserting null cycles, typically at a rate of 50-70%
of the total number of clock cycles. This results in the processor "resting" for 50-70% of the
time.
As the die temperature drops, the TCC will gradually reduce the number of null cycles until no
more is required to keep the die temperature below the safe point. Then the thermal sensor
turns the TCC off. This mechanism allows the processor to dynamically adjust its duty cycles
to ensure its die temperature remains within safe limits.
The Delay Prior To Thermal BIOS feature controls the activation of the Thermal Monitor's
automatic mode. It allows you to determine when the Pentium 4's Thermal Monitor should be
activated in automatic mode after the system boots. For example, with the default value of 16
Minutes, the BIOS activates the Thermal Monitor in automatic mode 16 minutes after the
system starts booting up.
Generally, the Thermal Monitor should not be activated immediately on booting, as the
processor will be under a heavy load during the booting process. This causes a sharp rise in
die temperature from its cold state. Because it takes time for the thermal output to radiate from
the die to the heat sink, the thermal sensor will register the sudden spike in die temperature
and prematurely activate the TCC. This unnecessarily reduces the processor's performance
during the booting up process.
Therefore, to ensure optimal booting performance, the activation of the Thermal Monitor must
be delayed for a set period of time.
It is recommended that you set this BIOS feature to the lowest value (in minutes) that exceeds
the time it takes to fully boot up your computer. For example, if it takes 5 minutes to fully boot
up your system, you should select 8 Minutes.
You should not select a delay value that is unnecessarily long. Without the Thermal Monitor,
your processor may heat up to a critical temperature (approximately 135°C), at which point the
thermal sensor shuts down your processor by removing the core voltage within 0.5 seconds.
4 Min / 8 Min / 16 Min / 32 Min
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