Intel D975XBX - Manual (Page 19)

Desktop Board Features
19
ACPI
ACPI gives the operating system direct control over the power management and Plug and Play
functions of a computer. The use of ACPI with the desktop board requires an operating system that
provides full ACPI support.
Fan Connectors
Desktop Board D975XBX has three chassis fan connectors (two 3-pin and one 4-pin) and one
processor fan connector (4-pin).
Fan Speed Control (Intel
®
Precision Cooling Technology)
Intel Precision Cooling Technology automatically adjusts the processor fan speed based on the
processor temperature and adjusts the chassis fan speeds depending on the system temperature.
System fan noise may be reduced by operating controlled chassis and processor fans at the
minimum necessary speeds.
The processor and chassis fan speed control features can be disabled independently through the
desktop board BIOS. Disabling the processor fan speed control will result in the fan operating at
full speed if it is not a self controlled fan. It is recommended that processor fan speed control
remain enabled (default BIOS setting) when using the processor fan heat-sink included with Intel
®
boxed processors. Disabling the chassis fan speed control results in chassis fans always operating
at full speed. The chassis fan speed control feature should be disabled if a self-controlled chassis
fan is attached to any controlled chassis fan header.
The overall system noise reduction will vary based on system configuration and environment.
Suspend to RAM (Instantly Available PC Technology)
CAUTION
For Instantly Available PC technology, the 5 V standby line for the power supply must be capable
of delivering adequate +5 V standby current. Failure to provide adequate standby current when
using this feature can damage the power supply and/or affect ACPI S3 sleep state functionality.
CAUTION
Power supplies used with this desktop board must be able to provide enough standby current to
support the standard Instantly Available (ACPI S3 sleep state) configuration. If the standby
current necessary to support multiple wake events from the PCI and/or USB buses exceeds power
supply capacity, the desktop board may lose register settings stored in memory.
Instantly Available PC technology enables the board to enter the ACPI S3 (Suspend-to-RAM) sleep
state. While in the S3 sleep state, the computer will appear to be off. When signaled by a wake-up
device or event, the system quickly returns to its last known awake state.
The desktop board’s standby power indicator, shown in Figure 3, is lit when there is standby power
to the system. This includes the memory modules and PCI bus connectors, even when the
computer appears to be off.
If the system has a dual-colored power LED on the front panel, the sleep state is indicated by the
LED turning amber.