Heat Sink Physical Installation Procedure

This procedure describes how to install a heat sink onto a conventional, socketed system processor. Modern CPUs require special cooling to ensure that they function properly, and the heat sink must be installed correctly to ensure that it does its job. Some processors come with an integrated heat sink and fan, and if you are installing one of these then you do not need to follow this procedure. I cover the installation of both passive heat sinks and active heat sinks (those that include a fan) here.

Procedure Overview:

Difficulty Level: 2 (Low).
Risk Factor: 1 (Very low). This assumes the CPU is already in the socket, otherwise the risk of damaging the CPU increases significantly.
Hardware Required: Heat sink compound.
Software Required: None.
Time to Perform: Less than 5 minutes
Preparation / Warnings:

This procedure assumes that the processor has already been installed into the motherboard. You can attach some heat sinks to a loose CPU as well, but some require the socket to secure properly to the chip.
If you want to double-check the markings on the CPU, for example to make sure that it has not been remarked, you will want of course to do this now, before you install the heat sink.
This procedure does not provide instructions for heat sink installation onto Pentium II processors (which are not socketed but use the SEC packaging format).


Procedure Steps:

Attach Fan to Heat Sink: Some active heat sinks come with the fan not actually attached to the heat sink. If yours is like this, then attach the fan to the fins of the heat sink now. This is usually done by screwing the fan into the heat sink using four screws supplied with it.

Apply Heat Sink Compound:
Open up the heat sink compound and apply a thin layer to the surface of the CPU using your finger. The layer should just be thick enough to obscure the surface of the chip. On CPUs that are totally flat, go almost all the way to the edges. On CPUs that have a raised metal plate in the center, apply the compound almost to the edge of the plate; you should not try to spread it over the whole surface of the chip, just the raised area (this is how the package is designed). Do not apply too much compound--more is not better here, and too much will make a huge mess when you attach the heat sink.

Attach Heat Sink: Place the heat sink on the surface of the CPU. Then secure the heat sink to the processor. Some heat sinks simply slip over the edges of the processor and just kind of "sit there". Most newer ones use metal clips that attach to the processor socket. To apply these, slip one of the metal clips over the plastic nub on one side of the socket, then stretch the clip across the CPU and over the nub on the other side. It may take a bit of pressure to bend the metal clip so that it will fit over the socket; this is what forces the heat sink onto the processor to ensure good contact. Just don't press too hard.

Warning: The suction formed by the heat sink compound can cause the heatsink to bond tightly to the CPU. In the next step you will be instructed to pull the heat sink straight off the CPU without sliding it. Only do this if you can do it without using excessive force, or you may damage the processor.

Check and Adjust Heat Sink Compound: Carefully remove the heat sink, by loosening it and lifting it straight up off the processor (don't slide it off, but bear in mind the warning immediately above). Then look carefully at the heat sink compound on the processor. You may see some areas where the heat sink compound is still smooth from where you applied it with your finger, and other areas where it has been disturbed (it may have a stippled appearance here, like a stucco ceiling). The disturbed areas are where the heat sink was making contact with the heat sink compound; the smooth areas are where it was not touching. In the areas that were not making good contact, apply a small amount of additional compound. Then reattach the heat sink. Repeat this step as necessary until you have good contact over most of the surface area of the chip.

Clean Up (If Necessary): If you're like me, you'll apply too much heat sink compound the first few times you do this. :^) Check around the perimeter of the CPU for extra compound that has oozed out from between the heat sink and CPU, and wipe it up. Do it now, because once the processor heats up the compound becomes more liquid and will make an enormous mess.


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