Dell Dimension 8400 - Manual (Page 29)

5. To remove the processor from the socket, lift the processor vertically in one motion.
Leave the release lever extended in the release position so that the socket is ready for the new processor.
Installing the Processor
1. Unpack the new processor.
2. If the release lever on the socket is not fully extended, move it to that position.
3. Align the pin-1 corners of the processor and socket.
4. Set the processor lightly in the socket and ensure that the processor is level in the socket. When the processor is positioned correctly, press it with
minimal pressure to seat it.
5. When the processor is fully seated in the socket, close the processor cover.
Ensure that the tab on the processor cover is positioned underneath the center cover latch on the socket.
NOTICE: Ground yourself by touching an unpainted metal surface on the back of the computer.
NOTICE: You must position the processor correctly in the socket to avoid permanent damage to the processor and the computer when you turn on the
computer.
NOTICE: To avoid damage, ensure that the processor aligns properly with the socket, and do not use excessive force when you install the processor.
NOTICE: Be careful not to touch or bend the pins on the system board.