Fan Domains; Nominal Fan Speed; Table 35. System Fan Domains - Intel X38ML - Server Board Motherboard Technical Manual

Platform Management
used to manually force the fan domain speed to a selected value, overriding any other control or
policy.
The fan domain state is controlled by several factors. They are listed below in order of
precedence, from high to low:
Boost
An associated fan is in a critical state or missing. The reference document describes
-
which fan domains are boosted in response to a fan failure or removal in each
domain.
Any associated temperature sensor is in a critical state. The reference document
-
describes which temperature threshold violations cause fan boost for each fan
domain.
The chassis cover is missing.
-
If any of the above conditions apply, the fans are set to a fixed boost state speed,
-
specified in the Tcontrol OEM SDRs.
Sleep
No boost conditions, system in ACPI S1 sleep state. In this situation, fans are set to
-
a fixed sleep state speed, specified in the Tcontrol OEM SDRs. The BMC can
support normal fan speed control in the S1 sleep state, so the BIOS does not enable
APCI fan control.
Nominal
See Section 5.16.2.
-
5.16.1

Fan Domains

System fan speeds are controlled through pulse width modulation (PWM) signals, which are
driven separately for each domain by integrated PWM hardware. Fan speed is changed by
adjusting the duty-cycle, which is the percentage of time the signal is driven high in each pulse.
The BMC controls the average duty-cycle of each PWM signal through direct manipulation of
the integrated PWM control registers.
The same device may drive multiple PWM signals. For system-specific fan domains,
see Table 35.
Domain
0 System Fan 1 (refer to Figure 1 label 29.)
1 System Fan 2 (refer to Figure 1 label 30.)
2 System Fan 3 (refer to Figure 1 label 31.)
5.16.2

Nominal Fan Speed

You can configure a fan domain's nominal fan speed as static (fixed value) or it can be
controlled by the state of one or more associated temperature sensors.
70

Table 35. System Fan Domains

Location
Intel order number E15331-006
Intel® Server Board X38ML
Fans
DIMM Fan
Use for other chassis
CPU blower
Output
PWM0
PWM1
PWM2
Revision 1.3