Asus P5GC-MX/1333 - Manual (Page 26)

1-14 Chapter 1: Product introduction
4. Remove the heatsink and fan
assembly from the motherboard.
5. Rotate each fastener clockwise
to reset the orientation.
The narrow end of the
groove should point outward
after resetting. (The photo
shows the groove shaded
for emphasis.)
Narrow end of the groove