An often misunderstood and sometimes overlooked critical hardware component is thermal interface material or TIM. TIM is typically seen as a thermal pad on a CPU heatsink, or in paste form. It may also be called thermal grease, silicon grease, heat transfer compound, thermal paste, heat sink compound, or goop. There are probably several more names.

The purpose of TIM is to ensure all the microscopic pits and valleys in the CPU die and heatsink mating surfaces are void of heat trapping air, maximizing surface to surface contact. Any excess is too much and gets in the way, and can actually be counterproductive to the heat transfer process.

The 4 Most Common Heatsink Fan (HSF) Assembly Mounting Mistakes:

1. Failure to use TIM
2. Used too much TIM
3. Reused old TIM
4. Did not clean mating surfaces thoroughly before applying TIM

Materials Needed: One clean plastic shaft Q-Tip (cotton swab), acetone or 91% isopropyl alcohol (Note - most rubbing alcohol is 70% and leaves a film. 91% alcohol can be found at your local drug store), clean scissors, can of compressed dusting gas, and the TIM. I recommend one of the new generations of non-metallic TIMs such as AC MX-2, Tuniq TX-2 or, OCZ Freeze or the venerable silver based TIM, Arctic Silver 5.

WARNING: Keep yourself grounded with the case to ensure there is no static buildup and discharge that might destroy any electrostatic discharge (ESD) sensitive devices. It is important to realize that the "threshold for human awareness" for a static shock is higher than the tolerance of ESD sensitive devices. In other words, you can shock and destroy a CPU, RAM module, or other sensitive device without even knowing there was a static discharge! Use an anti-static wrist-strap or frequently touch bare metal on the case to maintain your body at the same potential as chassis (case) ground.

Preparation: Power off and unplug the computer from the wall. Cut off one cotton swap near the end. Bend the plastic shaft about 1/2 inch from the cut end to make a nice little hockey stick. This is the working end of your TIM application device. Clean the die and heat sink mating surfaces with a soft, lint free cloth dampened (not dripping wet) with acetone or 91% alcohol. Do not let any fluids run down the sides of the CPU die. Clean skin oils from the working end of your applicator with the alcohol dampened cloth. Blast the surfaces with a quick blast of compressed air to ensure the surfaces are dry and no lint or dust remains behind. Do NOT touch the CPU die or heatsink mating surfaces, or the applicator's working end from this point on.

Application: Apply one "drop" of paste, about the size of a grain of rice, on the corner of the die and spread it out across the die with the applicator, like spreading icing on a cake. Spread the paste as thin as possible while ensuring complete coverage. It is easier to add more than remove excess. Remember, too much is counterproductive.

Note 1: Depending on the type of TIM used, some, such as the silver based compounds, can take 2 - 5 days or longer (depending on the power/heat up-cool down cycles) for the TIM to cure and reach optimum effectiveness. A 2 – 4°C drop in average temperatures may be realized after curing.

Note 2: A new HSF may come with a thermal interface pad already applied. Those pads consist of mostly paraffin, which is supposed to melt and squirm out of the way when the CPU heats up for the first time. Thermal pads are certainly better than no TIM at all, but they are not as effective as silver or ceramic based compounds. Do not use a sharp or metal object to remove the pad. A fingernail will work fine, removing any residue with acetone or alcohol.

Note 3: Do not reuse a thermal pad or paste. Always remove the old, cured TIM, clean the mating surfaces thoroughly, and apply a fresh application of new TIM.

Note 4: Thermal adhesive is a specific type of TIM used to permanently or semi-permanently glue heatsinks to devices that have no other heatsink mounting mechanism. Thermal adhesive is NOT intended to be used between a CPU and the CPU heatsink.

Note 5: TIM is also used to ensure maximum heat transfer to the heatsink from graphics processor units (GPUs), chipsets, graphics card memory modules, and other devices. Adhesive TIM, as mentioned in the note above, is often used on these devices as many do not have mounting brackets or holes to support a clamping mechanism. When mounting a heatsink to one of these components, the idea is the same; apply as thin a layer of TIM as possible, while still ensuring complete coverage.

See Benchmark Reviews 33-Way TIM Comparison or TweakTown TIM Review for additional information.
***********

Edit History
12/16/10 - clarified size of a "drop" - Digerati
12/16/10 - Added recommended TIM - Digerati
11/15/10 - Minor formatting edits - Digerati
3/22/09 - Minor edits - Digerati
9/20/08 - Added Benchmark Review link - Digerati
4/22/08 - Added note concerning using TIM with other devices, such as GPUs - Digerati
1/19/08 - Added reference to MX-2 and tweaked text throughout - Digerati
11/17/07 - Added reference to Tuniq TX-2, removed reference to AS Céramique - Digerati

Just to add, AS5 is not the only one that'll do. Try Arctic Cooling MX-1 and MX-2 if you can, they are superior to AS5, and another one a little better than these is Shin Etsu.

The difference between AC MX-1 and AC AS5 was 9ºC idle and 7ºC load that I tried with a 3GHz E6850 7 weeks back BTW, and I'm not kidding either. Very worthwhile gains if you know what you're doing and do not apply too much nor too little, but make sure your HSF base has a good even contact with the CPU.

I updated the sticky above to include Tuniq TX-2, a relatively new TIM with the main characteristics being non-metallic (hence the reason to remove my recommendation for AS Céramique - still a fine product, however), outstanding heat transfer properties, and no curing time. Its heat transfer properties compare favorably with Arctic Cooling's MX-2, which I also endorse. However, it is less expensive than MX-2, and therefore, gets my nod.

I do not agree with the above assessment that AC MX-1 is superior to AS5 as my own experience would indicate otherwise (once allowances for curing time is considered). It is superior to AS Céramique, however. Having said that, MX-1 is superior to thermal pads and to plain old silicone grease so if you have some laying around, don't hesitate to use it.

Bottom line, however, is don't go without some sort of TIM - even those little free packets of plain old silicone grease is far superior to nothing! If you are using a current technology, cool running CPU and no overclocking, the TIM that comes with your CPU/HSF will probably be more than adequate (along with good front-to-back airflow through the case).

Attachment 1527

Attachment 1528

Attachment 1529

Jephree told me I should post here to let you guys see what I'm dealing with. My original post is in Hardware upgrades under Rocky ll RT 686. I just removed this panel looking for RAM sticks and bit off a little more than I can chew. Saved this thread in favorites to try and repair what I took apart. I am a Harley mech, not computer tech, But I get adventerous and bold. Any tips besides whats already posted would be very much appreciated. Jephree helped me a bunch. I dont know how to make the pictures smaller so please exuse.

I would start with some Acetone or 91% alcohol and cotton pads and start cleaning.

!10-4, Gotcha, Will begin tommorrow. The adventure begins.

When you come back, how about starting a new thread? That way, this thread can stay on point about TIM.

Thanks.