Asus P5GC-MX - 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