How to Install a CPU and Heatsink

Add a new processor and cooling system to your PC

If you're building your own PC, then you'll need to know how to install a CPU onto the motherboard. You must also attach a heatsink fan on top of the processor to keep it cool.

Instructions in this article apply to the pin-grid array processor design used by most manufacturers.

A gold color heatsink on computer main-board
Jfanchin / Getty Images 

Choosing the Right Processor

Motherboards only support specific brands and types of processors, so read all documentation for your motherboard and processor before proceeding. In addition, refer to the documentation for the motherboard, processor, and cooling unit. You'll need to know the locations of the processor slot, heatsink mounting clips, and the CPU fan header.

How to Install a CPU and Heatsink

These instructions assume that you are installing the CPU onto the motherboard before installing the motherboard into the computer case:

The steps for replacing an existing processor are the same, but you must first remove the original CPU by reversing the installation instructions.

  1. Locate the processor socket on the motherboard and open the processor slot by lifting the lever on the side to the open position.

    A hand opening the CPU socket on a motherboard
  2. Locate the keyed portion of the processor that is signified by a diagonal corner of the pin layout. Align the processor so that this corner matches up between the processor and the socket.

    A hand aligning the CPU to the socket on a motherboard
  3. With the processor aligned based on the key, make sure the pins are lined up with the socket and gently lower the CPU so that all the pins are in the proper holes.

    Insert the CPU
  4. Lock the CPU into place by lowering the lever on the side of the processor slot until it is in the locked position.

    If the processor or cooling solution came with a protection plate, align it over the processor as instructed with the product documentation.

    A hand locking a processor in place on a motherboard
  5. Apply a thermal pad or several rice-sized drops of thermal paste to the exposed portion of the processor. If using paste, be sure it is spread in an even thin layer across the whole portion of the processor that will be in contact with the heatsink.

    It is best to spread the paste evenly by covering your finger with a clean plastic bag. This prevents the paste from being contaminated.

    Thermal compound being applied to a motherboard
  6. Align the heatsink or cooling solution above the processor so that the clamps are in line with the mounting points around the processor.

    A hand aligns the heatsink over a CPU
  7. Clamp the heatsink in place using the proper mounting technique required by the solution. This may be done by lifting a tab over a mounting clip, or by screwing the heatsink to the board. Refer to the documentation for the heatsink to ensure proper installation.

    Be careful at this stage as a lot of pressure will be placed on the board. A slip of a screwdriver can cause a lot of damage to the motherboard.

    A hand attaching a heatsink to a motherboard with a screw driver
  8. Locate the power lead for the cooling solution's fan and the CPU fan header on the motherboard. Plug the power connector for the cooling unit into the fan header on the board. It should be keyed, but make sure it is secure.

    A hand attaching a heatsink fan header to a motherboard

When all the remaining parts necessary for operation are installed, the motherboard BIOS must either detect or be told what type of processor is installed on the board. Refer to the documentation that came with the computer or motherboard on how to configure the BIOS for the proper CPU model.