[SOLVED] Thermal paste to mitigate surface imperfections vs total ihs coverage

boju

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So rice grain blob is usually recommended, even by Intel. Some say X or line for coverage, I'd say that would be too much paste forming that amount resulting being an insulator. However, too little, then the entire ihs isn't completely covered. For maximum heat transfer to heatsink, since complete metal to metal surface contact is preferred but obviously not possible even machine wise, there would assume be other areas between ihs and cooler not in rice grain's coverage that wouldn't be influencing efficient contact. Would having entire surface between ihs and heatsink be best spread thin or just a grain blob in middle really be enough?
 

Karadjgne

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Pea or rice used to be fine, when cpus were all monolithic die and relatively small compared to the IHS and the biggest TDP was barely hitting 100-125w area. Gpu repaste, liquid metal, absolutely demands a full spread, not a blob or X or smiley face, Ryzen generally are not monolithic, 12th gen isn't so small a die, so being in the habit of full thin spread isn't exactly a bad idea.
 
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geofelt

Titan
The purpose of paste is to fill in small air pits in the mating surfaces.
Paste is a better conductor of heat than air.
But, paste is not as good as metal to metal.
Usually, in the past, a small drop will spread out under heat and pressure.
Pretty much in a circular pattern.
You want enough paste to spread out to near the edges of the die, but not so much that it overflows the die.
With larger less square dies, that may be more difficult to cover with a circular pattern.
I would hope the center is where the hottest components are.
The risk with lines or x'es is that some air will get trapped during the spread and reduce the effectiveness.

No doubt, there will be some tests of this with alder lake.
For now, I would not worry much. any technique is going to give satisfactory results without significant performance differences.
 
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So rice grain blob is usually recommended, even by Intel. Some say X or line for coverage, I'd say that would be too much paste forming that amount resulting being an insulator. However, too little, then the entire ihs isn't completely covered. For maximum heat transfer to heatsink, since complete metal to metal surface contact is preferred but obviously not possible even machine wise, there would assume be other areas between ihs and cooler not in rice grain's coverage that wouldn't be influencing efficient contact. Would having entire surface between ihs and heatsink be best spread thin or just a grain blob in middle really be enough?
Assuming the paste resembles some kind of fluid, you can't really have "too much" thermal paste because the mounting pressure will squeeze it out. All you're doing is making a mess or a disaster if the paste is electrically conductive.

As for how much of a glob to put down, as long as it covers most of the IHS after mounting the heat sink, the how you put down the glob doesn't matter. And if you're not sure if it covers most of the IHS, mount the heat sink like normal, then take it off. If the thermal paste didn't cover most of the IHS, add a tiny bit more where it's needed and remount. Or if you don't want to do that, you can spread it around.
 
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Oct 30, 2021
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Assuming the paste resembles some kind of fluid, you can't really have "too much" thermal paste because the mounting pressure will squeeze it out. All you're doing is making a mess or a disaster if the paste is electrically conductive.

As for how much of a glob to put down, as long as it covers most of the IHS after mounting the heat sink, the how you put down the glob doesn't matter. And if you're not sure if it covers most of the IHS, mount the heat sink like normal, then take it off. If the thermal paste didn't cover most of the IHS, add a tiny bit more where it's needed and remount. Or if you don't want to do that, you can spread it around.
Watched a vid on it. Its not how you do it but how much. Not enough seems more of an issue then over doing it although ive always used the cotton swab, credit card method. That and the kind of thermal paste. Has always netted me better than average results. Noctua nh1 . Non conductive.
 

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