Heatsink and Shim Installation

Author: Nick Curtiss webmaster@crazypc.com

Date: 12/6/01

I'm always being asked about how to install heatsinks, how to apply thermal grease, and how to use a shim. Well, I finally decided it was time to write a small "how-to" that would cover these topics. As always, I don't claim to be an expert; just sharing my experience in this article and I welcome any constructive comments that you want to throw my way.

Installing a heatsink isn't all that tough a job (most of the time), it's best to take your time and make sure you're doing it right. After all, we don't want to fry that nice new processor you've been aching to try out, now do we? Ah, how many times have I heard someone who has toasted their CPU, just because they didn't take the time to check if the heatsink was properly installed. So, the number one rule is to do a practice run and make sure you have good contact between the heatsink and CPU. I may be getting a little ahead of myself. Let's start with the basic tools and materials we'll need:

• Heatsink
• Thermal grease
• Screwdriver with a wide flat blade (non-magnetic is preferred!)
• Anti-Static grounding strap
• Non-conductive CPU shim (optional but we highly recommend it)
• Isopropyl Alcohol (high quality please)
• Cotton swabs and lint free tissue paper (lense cleaner, coffee filters...)
• A straight edge razer or equivalent
• Mineral Spirits (or a suitable solvent of your choosing. I also like Goof Off)
• CPU (if you don't have one, you can stop reading now)

The first step is to clean the CPU and heatsink. I like to clean both using a solvent like miner spirits or Goof Off. Both of these will do a good job cutting through grease and gunk, especially if you're cleaning off some old thermal compound. I use a cotton swab or que tips to clean both the bottom of the heatsink and the CPU core. We only need to clean the CPU core itself. It's unnecessary to clean anywhere else on the chip, since it won't be contacting the heatsink. After I clean up with the solvent, I finish cleaning with Isopropyl Alcohol (get some good quality stuff. It should be under $5). I use a lint free tissue for this job, and clean both the heatsink bottom and CPU core again. Just let that dry off before going to the next step.

Now that we have a nice clean heatsink and CPU core, we can get our thermal grease ready for application. I like to squeeze a small dab of thermal grease onto a small plastic plate (clean the plate please). I'll scoop this up with an exacto razer blade that I use as my trowel for spreading on the grease. Arctic Silver is my thermal grease of choice. I put a small amount (about the size of a rice grain or two) on my blade, and smooth this over the surface of the CPU core. I try to get a nice thin and even application on the core. It's going to be thin enough to just cover the core so I can't see it, but not so much grease that it's going to gush all over once I press the heatsink down onto the core. The grease is used to fill in the tiny gaps between the surface of the heatsink and the CPU core.

Before we attach the heatsink, I've decided to use a non-conductive shim. A shim isn't necessary, but I recommend them now for a couple of reasons.  (Frankly, I just didn't have the guts to use the copper shims when they first came out, but with these new non-conductive shims there's absolutely no risk of shorting.) I like to use the shim mainly because they help protect the processor from accidental damage while installing the heatsink, and most importantly they help keep the heatsink level.

At last, I'm ready to put the heatsink on. The heatsink I'm using for this demonstration is the Vantec CCK-6027D. Like most heatsinks with a conventional metal clip, it has a front side and a back side. It's very important to identify the front and back as this is crucial to getting a level seat on the CPU core. First, take a look at the Socket A/462 in the diagram to the right. Note the green arrow indicates the front of the socket and the red arrow indicates the back. Also, note the raised plastic header on the front side of the socket. Now, I can identify the front of the heatsink in two ways. Most heatsinks will have one side of the bottom that is notched out or recessed. This is to clear the raised plastic header on the front of the socket. Another way to identify the front end of the heatsink is by the clip itself. In many cases, the clip will have a swivel hook, thumb depressor, or notch for a screw driver. In contrast, the back end of the clip will just be a plain old hook. As mentioned above, some clips are designed so that they can be depressed using your fingers, in other cases it might be necessary to use a screwdriver. The CCK-6027D has a notched tab on the front hook that is designed so that a flat head screwdriver can be used to push down on the clip. 

Front of Clip	Back of Clip

Now that I am sure which end of the heatsink goes to the front of the socket A, I'm ready to start. First, I attach the back end of the clip on to the back middle tab of the socket A. In order to do this, I have to tilt the heatsink back on an angle so that the clip will hook around the plastic tab. Once it's hooked, I can slowly and firmly push down on the heatsink until it is flat with the CPU core. Being right handed, I use my left hand to hold the heatsink in place for the next bit. Taking my flat head screw driver*, I place it in the notch on the front clip and push down until it hooks on the front plastic tab. I'm extra careful in doing this as it requires some force to push the clip down and on to the plastic tab. It's important the the screw driver is firmly seated in the metal tab so it won't slip out.

* - Tip: To avoid damage to your motherboard. Customers have suggested taping a piece of cardboard or like material to the motherboard so if the screw driver slips it will help to prevent damage.

Finally, I've managed to get the heatsink on and it seems to be firmly attached and level. But, I'm not going to press the "on" button just yet. After all this hard work, I'm going to remove the heatsink and see how good the contact was between the CPU and heatsink. I can do this by removing it and looking at the impression left by the thermal grease on the bottom of the heatsink. I'm looking for a nice square impression and good coverage. Well, there it is. Look's pretty good to me. At this point, I will go through the installation steps again. If I'm feeling extra paranoid, I can perform one more additional check to ensure good contact, and that is to shine a light from behind the CPU. There should be no light coming between the CPU core and heatsink. One last thing to do before we can power-up. Remember to connect your fan to power!