Asus M4A89GTD PRO/USB3 - Manual (Page 24)

2-6 Chapter 2: Hardware information
Chapter 2
3. Position the CPU above the socket such
that the CPU corner with the gold triangle
matches the socket corner with a small
triangle.
4. Carefully insert the CPU into the socket
until it fits in place.
5. When the CPU is in place, push down the
socket lever to secure the CPU. The lever
clicks on the side tab to indicate that it is
locked.
Gold triangle
Small triangle
6. Apply some Thermal Interface Material
to the exposed area of the CPU that the
heatsink will be in contact with, ensuring
that it is spread in an even thin layer.
Some heatsinks come with pre-applied
thermal paste. If so, skip this step.
The Thermal Interface Material is toxic
and inedible. DO NOT eat it. If it gets into
your eyes or touches your skin, wash it
off immediately, and seek professional
medical help.
To prevent contaminating the paste, DO NOT spread the paste with your finger.