Specifications

SYSTEM MANAGEMENT
PP 41x/03x 11-3
11.2.4 PC BIOS Setup Options
The PC BIOS Setup Menu provides control over the thermal management functions, using the
setting for the Advanced | Advanced Processor Options | Thermal Control
Circuit option. It offers four choices, namely:
• Disabled - only the Thermal Trip is enabled
• TM1 - the CPU’s clock modulation mechanism is used to reduce power consumption; the
Thermal Trip is enabled
• TM2 - the CPU operating frequency is lowered to reduce power consumption; the Thermal Trip
is enabled
• TM2 + TM1 - TM2 will be used during normal operation, however if this fails to keep the
operating temperature to an acceptable level TM1 will be invoked in addition.
The default setting is disabled.
It may be desirable that some form of thermal management is enabled to handle operation at very
high load and high temperature. Under normal conditions, even with high loads, the standard
heatsink and specified forced air cooling are adequate to keep the processor operating within its
limits even with the Thermal Management option set to Disabled. The BIOS setup option provides
a means to enable additional protection if there is any concern about heat dissipation in the
particular system being used.
11.2.5 Processor Thermal Status Indication
The User LED may be programmed to indicate if the processor die has reached the critical
temperature at which thermal management is activated. This is done using the User LED Mode
option switch. Figure 11-1 shows the location of this switch on the board, its settings and default
position.
Figure 11-1 User LED Mode Switch
The User LED will also indicate a CPU thermal trip. See Section 11.2.3 for details.