Delay Prior To Thermal
Common Options : 4 Minutes, 8 Minutes, 16 Minutes, 32 Minutes
Quick Review
The Delay Prior To Thermal BIOS feature is only valid for newer Intel processors (from the 0.13µ Intel Pentium 4 with 512 KB L2 cache “Prescott” onwards). These processors come with a Thermal Monitor which actually consists of a 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” 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 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.
Details
The Delay Prior To Thermal BIOS feature is only valid for newer Intel processors (from the 0.13µ Intel Pentium 4 with 512 KB L2 cache “Prescott” onwards). These processors come with a Thermal Monitor which actually consists of a on-die thermal sensor and a Thermal Control Circuit (TCC). Because the thermal sensor is on-die and placed at the hottest part of the die – near the integer ALU units, it is able to closely monitor the processor’s die temperature.
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 send a PROCHOT# (Processor Hot) signal which activates 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. Note that the operating frequency of the processor remains unchanged. The TCC only inserts null cycles which results in the processor “resting” 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 stops sending the PROCHOT# signal, thereby turning the TCC off. This mechanism allows the processor to dynamically adjust its duty cycles to ensure its die temperature remains within safe limits.
[adrotate banner=”5″]The Delay Prior To Thermal BIOS feature controls the activation of the Thermal Monitor’s automatic mode. It allows you to determine when the 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.
It also allows the watchdog timer to generate a System Management Interrupt (SMI), thereby presenting the BIOS with an opportunity to enable the Thermal Monitor when running non-ACPI-compliant operating systems.
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. This allows the processor to operate at maximum performance without interference from the Thermal Monitor. It also prevents the unnecessary activation of the TCC and the subsequent modulation of processor cycles by allowing the die to stabilize to its true temperature before Thermal Monitor is activated.
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 THERMTRIP# signal will be asserted. This shuts down your processor by removing the core voltage within 0.5 seconds. While this measure will most likely save the processor from permanent damage, you will be forced to reset the system before the processor will start working again.
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