With a full weekend spend testing several very messy thermal interface materials and running up a power bill, I was pleased to complete testing and announce the final five products. Now obviously, you could skip everything I am about to tell you, and just simply read the results and be on your way; but then you would miss my insider notes. This project started as a 33-Way Thermal Interface Material (TIM) Compound Performance Comparison Review, and it ends with only five, but there were several products that really deserve some credit for making it this far.

Although this each round of testing was very controlled, there will always be small differences discovered with each new test. Obviously one TIM might perform slightly different from test to test, but this final round is a collection of those products which proved themselves consistent performers.

In what I would consider the biggest surprise of the entire test series, the white silicon-based TIM provided with every Thermalright CPU cooler product really earned a name for itself. Most manufacturers enclose a small packet of white thermal grease with their coolers, while selling a premium product separately. Thermalright actually offers their very noteworthy "Chill Factor" thermal grease "for free", and I can appreciate that after spending so much on their product. It's a real shame that other manufacturers do not follow this lead, and match their premium cooling product with their premium thermal compound.

Other products did very well, but have very little chance of ever finding store shelves. Our finest example is the TIM Consultants T-C Grease 0098, which performed very well in each round of testing, but is available from an obscure website that seems as low-tech as you can find.

Our final five show a very diverse collection of compound materials: from diamonds to silver, carbon to aluminum, and zinc to silicon, there's a little of everything represented here. Obviously these manufacturers keep their recipe closely guarded and secret, as to avoid duplication by the competition. The final result is a wide array of interface materials which arrive at the same result using different techniques. The only key ingredient which appears shared in all of these top-tier products is the use of aluminum-oxide, which gives the darkened grey appearance and conducts energy very well between compound components.

Alternative Opinions

After this article was first published, there was an immediate backlash from some of the manufacturers listed in this review. The primary argument was the lack of cure time. Here is the Arctic Silver 5 recommended cure time instruction from the manufacturers web site:

Due to the unique shape and sizes of the particles in Arctic Silver 5's conductive matrix, it will take a up to 200 hours and several thermal cycles to achieve maximum particle to particle thermal conduction and for the heatsink to CPU interface to reach maximum conductivity. (This period will be longer in a system without a fan on the heatsink or with a low speed fan on the heatsink.) On systems measuring actual internal core temperatures via the CPU's internal diode, the measured temperature will often drop 2C to 5C over this "break-in" period. This break-in will occur during the normal use of the computer as long as the computer is turned off from time to time and the interface is allowed to cool to room temperature. Once the break-in is complete, the computer can be left on if desired.

So by my estimation of this statement it would take almost a year of normal use to properly cure the AC5 compound, or almost nine days of continuous power cycles to meet their recommendation. Benchmark Reviews feels that this is a characteristically unreasonable requirement for any TIM product, and we do not support it. We want products that perform without the burden of sacrifice on our time, especially with some many competing products offering performance without this extra requirement.

Some enthusiasts might seem left out, since this review concentrated its efforts on air-cooled solutions. By nature, air-cooled products do not create condensation between materials because they are always operating above ambient temperatures. There is good reason for the exclusion of liquid-cooled reference in this article, and that is because processors have reduced their thermal output to such a point to where air cooling today is more effective than liquid-cooling years ago.

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