iFixit

Grab the processor by its edges and lift it straight up off its socket.

Rotating the processor while lifting it out has the potential to break pins off inside the socket. Lift it straight up.

Processors are extremely sensitive to electrostatic discharge. Only handle your processor by its edges.

To aid in installation, processors and sockets have a small alignment arrow (shown in red) so the chip is installed in the correct orientation.

Align the chip so that the arrow in its upper right corner corresponds to the arrow molded into the upper right corner of the socket.

Carefully lower the processor onto its socket.

Note that if you are upgrading from a core solo or core duo processor to a core 2 duo processor and wish to run operating systems of Leopard or later, you must delete the hidden file /System/Library/CoreServices/PlatformSupport.plist after the upgrade.

Use a small flathead screwdriver to rotate the processor lock 180 degrees clockwise until the indicator points toward the closed lock symbol.

Now that the processor is in place, turn your attention to the heat sink.

Apple uses a thermally conductive film that must be removed prior to reinstalling the heat sink.

Use a razor blade (or anyother flat object such as a credit card, etc.) to remove all of the old solidified thermal material from the heat sink.

Next use a small amount of rubbing alcohol to remove all traces of the old thermal material.

Allow the heat sink to dry before proceeding.

Apply a thin layer of thermal paste to the reflective silicon face of the processor.

Check out our thermal paste guide for detailed instructions on applying thermal paste.

Lay the heat sink on the AirPort card and use a spudger to reconnect the heat sink thermal sensor.

Position the heat sink the same way it will permanently sit before lowering it onto the processor to avoid spreading thermal paste on regions not in contact with the processor.

Gently lower the heat sink onto the processor.

While holding the heat sink in place, press the four plastic posts down through the logic board to reattach the heat sink.