Asus P5K Premium/WiFi-AP - Manual (Page 38)

2-12 Chapter 2: Hardware information
5. Rotate each fastener clockwise to
ensure correct orientation when
reinstalling.
Narrow end of the groove
Refer to the documentation in the boxed or stand-alone CPU fan package for
detailed information on CPU fan installation.
The narrow end of the
groove should point outward
after resetting. (The photo
shows the groove shaded for
emphasis.)