Gigabyte GA-H55M-S2V User Manual page 49

CPU Smart FAN Mode
Specifies how to control CPU fan speed. This item is configurable only if CPU Smart FAN Control is set
to Enabled.
Auto Lets the BIOS automatically detect the type of CPU fan installed and sets the optimal
CPU fan control mode. (Default)
Voltage Sets Voltage mode for a 3-pin CPU fan.
PWM Sets PWM mode for a 4-pin CPU fan.
Note: The Voltage mode can be set for a 3-pin CPU fan or a 4-pin CPU fan. However, for a 4-pin CPU
fan that is not designed following Intel PWM fan specifications, selecting PWM mode may not effectively
reduce the fan speed.
- 49 - BIOS Setup