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 Lion or later, you must delete the hidden file /System/Library/CoreServices/PlatformSupport.plist after the upgrade.