F71869A
5.2.11. Fan Speed Control Mechanism
There are some modes to control fan speed and they are 1.Manual mode, 2.Stage auto
mode 3. Linear auto mode. More detail, please refer the description of registers.
Each fan can be controlled by up to 8 kinds of temperature inputs: (1) D1+ temperature (2)
D2+ temperature (3) D3+ temperature (4) PECI temperature (5) 4 suits SMBus master
temperature. Each fan would make the maximum temperature comparison form those
inputs with the expected speed, and decide the suitable fan speed. Please refer below
figure 7.
PECI
(T0)
D1+ T
(T1)
Expected
Fan1
Fan2
speed1
D2+ T
(T2)
Expected
speed 2
D3+ T
(T3)
IBX
Byte1
Expeted
speed 3
Fan3
IBX
Byte3:2
IBX
Byte4
IBX
Byte5
Figure 7 Relative temperature fan control
Manual mode
For manual mode, it generally acts as software fan speed control.
Auto mode
In auto mode, the F71869A provides automatic fan speed control related to temperature
variation of CPU/GPU or the system. The F71869A can provide four temperature boundaries and five
intervals, and each interval has its related fan speed count. All these values should be set by BIOS
first. Take FAN1 for example, the 4 temperature boundaries could be set from register 0xA6 to 0xA9
and the five intervals for fan speed control could be set from register 0xAA to 0xAE. And the
28
Oct., 2011
V0.19P
FINTEK [ FEATURE INTEGRATION TECHNOLOGY INC. ]
