From when I ever first became aware of the existence of thermal compound also known as thermal paste, I thought that simply any thermal compound would do. However I was very much mistaken.
Thermal compound is essentially the paste that has to be applied between where the processor meets the heatsink. Thermal compound is usually a whitish or greyish colour and is typically a highly viscous paste. The compound has to be applied in certain ways for certain processors. This includes graphics processors, controller chips, Intel processors and AMD processors. There are also a variety of different ways to apply the compound based on the model of processor.
For example, in the past the standard way to apply thermal compound was to simply apply a small amount of thermal compound in a circular manner then simply use the pressure of the heat sink to compress the compound. A modern example of showing all of the different ways to apply thermal compound could be the application process of the first and second generations of Core i3, i5 and i7. On these processors, two methods are preferred, there’s the die line method and the complete surface area spreading method. Both of which depend on the thermal compound, the type of heatsink and which processor it is being applied to. The die line method is simply where the compound is applied with the thickness of about a grain of rice and a length of about 2-3 grains of rice across where the processor die sits just under the heat spreader.
So what advantages do high performance thermal compounds have and what are the differences?
Well lets start with the classic stock white or light grey compound that is usually just labelled “Thermal Compound” and costs pennies. This compound is the least effective and is quite often the culprit in the infamous PS3 YLOD problem. The compound is usually more of a cream texture and it tends to dry in quite a crusty manner. This paste however may work just as fine in some situations, particularly on low-heat-output processors.
So then we move on to the better performance compounds. This includes compounds such as the famous Arctic Silver 5, Arctic Cooling MX-4, Xigmatek Freezing Point, Tuniq TX-2 and Antec Formula 5. These compounds are usually more expensive than the conventional stock thermal compound, however they offer huge advantages. Arctic Silver 5 is a famous thermal compound which happens to have very small silver particles in it. The advantages with such a compound is of course extreme thermal conductivity. Whereas the stock thermal compound will usually have some degree of thermal resistance, thermal compounds at this performance level will have virtually no heat resistance. This essentially means that almost 100% of the heat output will travel to your cooler and then will subsequently be taken away by the means of a fan or a liquid cooling solution.
This compound also has other advantages due to it’s chemical formula such as the prevention to separate, migrate, bleed or run. This allows for a stable compound for use on your processor. I myself have used Arctic Silver 5 on my PS3. My PS3 (fat version) has been out of warranty for some time now and I already had experience in taking apart the PS3 system. I decided to add some Arctic Silver 5 to my PS3′s two processors to increase it’s cooling performance (it was getting quite noisy) and decrease the chance of YLOD (Yellow Light of Death). Upon opening up the console and separating the processors from their respective heatsinks, I noticed that the thermal paste was virtually none-existant. And the small remnants that were there where like small crusty pieces of chipped off paint. This was quite obviously the reasoning behind the high fan speed of my PS3. So I removed the old compound with a couple of alcoholic swabs and used the surface area spreading method to cover the entire surface of the processors. Overall the procedure made an amazing improvement. I thought adding this compound might make a small difference but the outcome was way above my expectations. The fan now stays at virtually the same start-up speed when the console is idle. Upon gaming, the fans do kick up, but nowhere near before. And as soon as I return to the home screen the fans decrease in speed again.
This really shows how much you can benefit from a good thermal compound. As mentioned previously there are many different compounds on the market and the ones listed above are regarded as some of the best performing compounds. My personal favourite is Arctic Cooling’s MX-4 thermal compound which is easier to apply than AS5 (Arctic Silver 5) and typically improves thermal conductivity by a few degrees. This compound is also non conductive and typically comes in a large syringe so you’ve got plenty for more compound jobs. Many say the disadvantage with AS5 is the curing time. This is essentially the initial 200 hour constant run-time to allow the compound to work it’s magic. During this time the compound will start to get thinner as the processor heats up to remove any air bubbles and to allow the compound to enter all of the various small ridges and gaps between the processor and heatsink. The processor will be at a slightly higher temperature at this stage. After this stage the thermal compound starts to thicken and becomes what it will be for the foreseeable future.
So these are the advantages (and a couple of disadvantages) of high performance thermal compound.