CPU before regreasing

Ever wondered why your laptop (or even desktop) PC sounds like a helicopter just trying to take off? Does it bother you to listen to your cooling fan all the time after turning on your computer? Well it does me too, so it is very important to know why this happens and what can be done to prevent (or at least mitigate) this problem. Those who are familiar with this topic probably should not read any further, as this little post will likely not contain any new information that they do not know already. But those, who just started to think of solving this problem for themselves and not wait for PC repair shops to do this, read on to discover how easy it is. In this post I will focus on laptops only, although the procedure also applies to desktop PCs as well with some minor differences.

Step #1: Understanding the basics.

The most important thing to understand here is that the cooling fan (obviously) cools some important parts of the PC, namely the CPU, and if a dedicated graphics chip (GPU) is installed, that too as well. Some notebook models have even more extesive heat sinks, which also cool the chipset and even memory chips of dedicated graphics cards. All these components might seem a lot to worry about, but don’t despair, as the vast majority of laptops sold for everyday use have integrated graphics chips, which nowadays are neatly packaged within a single component with the CPU, so most notebooks can be fixed extra easy.

So how are CPUs kept cool? The vast majority of laptops (if not all of them) are cooled by a special heat sink assembly which looks different from standard desktop coolers, as these need to be crammed in into tight spaces. Standard desktop PC heat sinks are usually built up of monoblock aluminum cooling grills (sometimes with a copper core) and a fan installed on top of it, but laptop heat sinks on the other hand are a bit more complicated. They have three main parts: the heat absorbing plate(s), heat pipe(s) and the cooler assembly, which itself is built up of 2 parts: the cooling fan and lamellae spread around it.

CPU heat sinks

There are two important things one needs to consider about heat sinks in general. One, is that however good the heat sinks are, they will never be able to transfer the right amount of heat away from the CPU package if the thermal contact between the two is inadequate. Since heat plates are not machined perfectly (due to cost considerations) and alignment is not always perfect, better thermal contact is achieved by applying a special thermal grease. These greases however, are not especially good thermal conductors, but as we will see shortly, are still far better than air. Here are some numbers (data provided for 20°C): air: ~0.026 W/(mK), copper: ~386 W/(mK) and thermal grease (depending on fillers): ~0.2-6 W/(m*K). Basically what one needs to understand from these numbers is that air is by far the worst heat conductor, greases are 10-100 times better than air, and copper is ~200-2000 better than greases. This information will have some important implications later, so it is good to remember these.

Medium thermal properties

The second thing that needs to be considered is where all the heat goes that was absorbed by the plate(s). Simply speaking, heat is channeled to the cooling lamellae via the heat pipe to be given off to the air flowing between lamellae. Although heat sinks have been designed to provide high enough contact areas between air and copper for heat exchange to happen, it is not enough, as because of the rather bad thermal properties of air, it will not absorb a lot of heat per unit of mass. This is overcome by constantly replacing air between lamellae (by a fan), which is also an important thing to keep in mind, as both the air flow and the thermal grease are well known bottlenecks of heat dissipation. Discrepancies happening with these two thus will in most cases be responsible for heightened fan usage and rotation speeds, so these are the areas one needs to check in laptops to fix the problem.

Step #2: Preparing for laptop disassembly

a) Now that we identified the possible sources of the problem, it is time to start doing things, which is disassembling your mobile computer. Unfortunately though, there is no general guide for accessing the heat sink in laptops, as laptops are not built as uniformly as desktop PCs to be able to provide a description that would fit all models. This means, that everyone has to figure out how to disassemble their own notebooks, but fortunately, there are several methods that will make this step relatively painless. The first and probably the best method everyone should use is to simply search youtube for disassembly videos of their particular laptop model. There are tons of such videos available, so finding the right one should be relatively easy. If for some reason this is not the case, one can look up videos for similar or previous models from the same product line, as the differences here will not be tremendous. If this one fails too (the previous two will work 99% of all cases), trying to look up the service manual is also a good idea, as that also will contain a detailed disassembly procedure. Finally, if nothing works, why not experiment a bit?

b) Get a good quality thermal paste. Silver loaded ones are quite good, so I recommend these, but pretty much any type of metal loading will vastly increase the thermal properties of the grease. Also, remember to check the metal concentration of the grease before buying, as a few percent of metal will unlikely have too much effect. Buy greases with several tens of percent metal loading at least (30 is OK) to have noticeable effect.
Note: DON’T start doing anything before you have a thermal paste, as you will not be able to reassemble the computer without it!

Good thermal paste

c) Get a compressed air can as it will save you a lot of trouble.

d) Get a soft cloth or paper. Soft paper towels worked good for me.

e) Some solvent like alcohol might also be a good idea to have, but it is not a necessity. Avoid using anything containing acetone on the other hand, as it might damage plastic components!

f) Also, before actually doing any disassembly, prepare a clean surface with as little clutter as possible, as there will be quite some screws and other parts that need to be placed in an organized manner during the whole procedure. Having everything organized and neatly placed will greatly help at reassembly later.

Step #3: Disassembling the laptop

In this guide I will show some major steps for disassembling a notebook computer (mine in this case), but keep in mind that it is by far not the most detailed one, as one can find videos of this, as mentioned before. So here we go:

a) Close display lid, remove power cord and batteries.

b) Examine how the heat sink can be accessed. Do you just need to remove a single plastic lid, or more extensive disassembly is required. Youtube videos are of really great help, so check them again!

c) Remove necessary lids, panels or palm rest.
Note: there might be some hidden screws under stickers or plastic lids so, checking youtube videos is crucial!
Note 2: placing the screws on a free surface of the table in an order as they were taken out to represent their real position is a VERY good idea, as not all screws are necessarily of the same size, so placing screws back to their original position is good practice.
Note 3: For removing the palm rest, in many cases the keyboard also needs to be removed, which means disconnecting some wires will be needed at this point. Not all connectors look the same, so check the images for the type you have.

d) Check how the heat sink is fixed to the motherboard. Sometimes there are screws holding the whole thing at the CPU only, but in some other cases the part at the fan is also fixed by a couple of screws. As stated before, laptop manufacturers don’t follow any standard guideline in designing the interiors, so a great variety of things exist.

Locate cooler assembly

e) Remove the screws holding the fan part first if you have any. After that, remove the screws holding the heat absorbing plate in place.
Note: the 4 screws should be unscrewed diagonally, and not clockwise or anticlockwise! In many cases the screws are numbered by the manufacturer, so going from 4 to 1 is a good idea. Also, never unscrew a screw entirely before moving to the next. A much better approach is to make a couple of turns on one screw, and then move to the next. Repeat this until all the screws become completely loose. This procedure will prevent any unnecessary uneven tension on the CPU surface.

f) Remove the heat sink very carefully.
Note: Try to avoid any horizontal movement to prevent scratching. Also, check for wires that might be in your way of removing the heat sink. In all cases you will need to disconnect the fan power supply wire, so note where it was connected exactly. Some other wires might also be clipped to the heat sink so be careful not to damage anything.

Step #4: Identifying the problem.

a) Carefully examine the surfaces of both CPU and heat absorbing plate. What you will likely see is dried or excessively used (or both) thermal grease. With the soft cloth you already prepared (Step #2) clean both surfaces completely, but remember not to push the cloth hard. Nobody wants any bends and cloth dust appearing on any of the surfaces.
Note: Remember: reusing old thermal paste is always a bad idea, so removing it is completely necessary. Dry grease has even worse thermal properties than the fresh one, not to mention if it was applied too excessively. Also, you don’t always know what kind of cheap stuff was applied before, so having it all gone is a good idea. One small syringe of good thermal paste is not that expensive and it will last long, so not using it is really out of the question.

Remove heat sink

b) Check the lamellae for dust collection. Use the air can to remove any dust.
Note: In many cases, especially if the computer was used on soft surfaces like bed covers, carpets, tablecloth, etc. the fan and lamellae will happily collect all the little dust particles that might detach themselves from these fabrics, and if enough time passes, the passages between lamellae will get clogged. This will obviously severely hinder air flow resulting in heightened fan usage as discussed in Step #1.

Check for dust

c) Check fan for dust collection. Use air can to remove any dust.
Note: Before using the air can or any other means to blow the dust out, temporarily brace the fan to prevent rotation! Too high rotation speeds due to air flow might damage your fan!

Step #5: Reassembling the computer

a) Apply thermal grease onto the CPU surface ONLY.
Note: As discussed in Step #1, thermal greases are not really good thermal conductors, so having as little as possible on the surface is what you want. Remember, that this is only needed to fill any possible air holes between the CPU and heat absorbing plate due to scratches and uneven positioning, so having too much of it is not justified. Actually, having too much might even increase the fan usage, which you are trying to minimize now, so be extremely careful how much you put on.
Note 2: There are several methods one can use to apply thermal grease.

Apply grease

I. Single drop method: Put a small drop onto the center of the CPU surface. Leave it as is, at reinstall the heat sink. The pressure applied by the heat sink mounting screws will disperse the grease evenly onto the entirety of the surface, so it is a pretty simple method. The disadvantages of it is that you really have to guess the amount of grease accurately, as having too little will not suffice to cover the whole surface, and having too much will both form to thick a layer and flow out from the surface to the sides. Remember, that metal loaded greases can be electrically conductive, so you might even risk damaging your computer if not careful.

II. Multi drop method: Put several even smaller drops at several points onto the CPU surface and reinstall heat sink. Apart from having the same problems as the previous method, this is also a bit less reliable if not done carefully, as this has a high chance of entrapping air bubbles while the grease spreads out from multiple spots due to pressure applied by the heat sink. I’ve seen a guy to use this method with great success for desktop PCs, but this is not recommended at all in notebooks, as special heat sink installation maneuvers are required for this to work, for which there is no adequate space in a laptop.

III. Spread method: Put some grease onto the surface of the CPU and spread it out evenly on the surface. You can either use a straight-cut piece of soft plastic, or one of your fingers to do this, but remember that you want a very thin layer of grease with uniform thickness and a surface without any grooves in it. Going through the grease layer multiple times with your finger or plastic is a good idea as it will remove some of the grease each time, allowing you to achieve an extremely thin coating. Any grease smeared onto the plastic casing of the CPU should be carefully removed by a soft cloth. I personally prefer this method, as it allows great control over the amount of grease, and with a little practice one can achieve very uniform coatings.

Regreasing methods

b) Reinstall the heat sink.
Note: When installing the heat sink, try to press the heat absorbing plate a little with a slight sideways moving to help the grease spread even better. Only after this put the screws back in.
Note 2: Don’t forget to reconnect the power cord for the fan!

c) Put back the covers, palm rest, keyboard and everything else as it was previously
Note: Don’t forget to properly reconnect keyboard and touchpad cords if these were also removed. A not properly reattached cord will cause erratic keyboard behavior.

d) Turn on computer and listen if the fan spins up. If it is, everything is fine.

Congratulations, now you know how to get through a simple re-grease procedure, and hopefully it will result in a more pleasant user experience.

P.S.: Some of the pictures found in this post are not mine but of their respective owners, no copyright infringement was intended.