In the BIOS under 'Hardware Monitor' there's a couple settings. Refer to pages 3-34~3-35 in the manual; also refer to 2-34 for which fan headers can be controlled (CPU_FAN & CHA_FAN 1 & 2) - http://www.asus.com/Motherboards/Intel_Socket_1366/P6T/#download (if needed select any OS then [+] Manual and download)
BIOS:
CPU Q-Fan Control -> Enable
> CPU Fan Profile -> Standard ; you can try others but IMO start with Standard
Chassis Q-Fan Control -> Enable
> Chassis Fan Profile -> Standard