How to Upgrade a P4C800 Processor
- 1). Shut down the computer and unplug it.
- 2). Remove the screws at the back of the case and slide off the side panel, exposing the motherboard.
- 3). Lift the levers holding the heatsink into place and lift the heatsink off of the CPU chip, exposing the processor.
- 4). Lift the retaining lever for the processor to release it from the socket and pull it away from the motherboard.
- 5). Insert the new processor in its place and lock it into position with the retaining lever. Mount the heatsink that came with your new processor according to the directions for your specific model.
Source...