Question Thermal paste to cpu or heat sink? Or both?

Aug 5, 2019
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Swapping out CPUs for first time not sure if I should apply thermal paste to cpu or heat sink. Also do I spread it or just smush it down?

Thanks!
 

britechguy

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Jul 2, 2019
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Apply to heat sink.

Use an amount that would be slightly smaller than a full-sized pea. Spread it out, but it can be in a line down the center and need not be "corner to corner. Pushing on the chip should force the paste to "fill in the blanks."
 
Aug 5, 2019
22
3
15
0
Apply to heat sink.

Use an amount that would be slightly smaller than a full-sized pea. Spread it out, but it can be in a line down the center and need not be "corner to corner. Pushing on the chip should force the paste to "fill in the blanks."
Thanks for the reply! Just one more question I’m cleaning off the old thermal paste but there’s some in the cracks is ok to apply the new paste or does it need to be removed from the cracks ? Here’s a picture View: https://imgur.com/a/qt3oxbM

Thanks again
 

britechguy

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Jul 2, 2019
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I certainly wouldn't go crazy trying to get that out.

That being said, get yourself a toothpick and scrape out what you can if you feel you must. A single pass, maybe two, in each crevice is the most you should do.

The new paste will "wed" with the old in the cracks. You never get rid of every single molecule of the old stuff.

Also, what did you use to clean it?

P.S. The layer of thermal paste, once compressed, is and should be very, very thin. If you get lots oozing out you've used too much (and clean that up with a swab).
 
Aug 5, 2019
22
3
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I certainly wouldn't go crazy trying to get that out.

That being said, get yourself a toothpick and scrape out what you can if you feel you must. A single pass, maybe two, in each crevice is the most you should do.

The new paste will "wed" with the old in the cracks. You never get rid of every single molecule of the old stuff.

Also, what did you use to clean it?

P.S. The layer of thermal paste, once compressed, is and should be very, very thin. If you get lots oozing out you've used too much (and clean that up with a swab).
I just used a coffee filter & it came off pretty easy paste was probably only 4-5 months old. Bought the board & old cpu together & the guy applied new paste. Thanks a lot for your detailed responses helping me a ton. 2nd time building a pc first time actually doing the thermal paste lol.
 

britechguy

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Jul 2, 2019
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You can use isopropyl alcohol or denatured alcohol to clean up old thermal paste. Just a tiny bit to moisten a piece of paper towel and a wipe or two usually does it.

A great many thermal pastes come with a couple of alcohol prep pads included.
 

Karadjgne

Titan
Herald
Apply to cpu not heatsink. The reason is your aim. Nobody is perfect, has perfect aim, you can easily be a few mm off when putting the heatsink down on the cpu. It's OK if the heatsink gets lopsided paste, but not ok for the cpu.

Just a small pea or large grain of rice sized blob is all you need, right smack in the center of the cpu. Pressure applied when you tighten the screws (do so incrementally, few turns each screw, back and forth until snug, evenly) will spread the paste where it needs to go.


The methods where paste is reaching over the sides are not usually recommended because of the potential for the paste to get into the socket. The smallish blob dead center is the preferred method.
 
Aug 5, 2019
22
3
15
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Apply to cpu not heatsink. The reason is your aim. Nobody is perfect, has perfect aim, you can easily be a few mm off when putting the heatsink down on the cpu. It's OK if the heatsink gets lopsided paste, but not ok for the cpu.

Just a small pea or large grain of rice sized blob is all you need, right smack in the center of the cpu. Pressure applied when you tighten the screws (do so incrementally, few turns each screw, back and forth until snug, evenly) will spread the paste where it needs to go.


The methods where paste is reaching over the sides are not usually recommended because of the potential for the paste to get into the socket. The smallish blob dead center is the preferred method.
Thanks for the response sadly ended up breaking my push pins lol
 

hotaru251

Reputable
Oct 30, 2014
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You never get rid of every single molecule of the old stuff.
i mean have you seen kingpins sonic washer?
and der8aur's MB in the dishwasher?




on topic:
the amount needed can vary.

You can watch many tech YT peoples channels and see the typical pea sized "can" be bad ta times (uneven pressure can force more to 1 side than other and you have a corner not covered).

tbh there is never really "too much" (within reason ofc) as excess will be squished out.
Full coverage is your goal (and why some ppl actually spread it over entire IHS for assurance). Just do it slow and little mixing as possible (to not trap large air bubbles...tiny ones have nearly no issue on performance as ppl have tested it)


also depending on the CPU model the makers have their own "rules"

like how with TR its an x with 4 dots between each line, skylake's midle line and corner dots, etc

also this vid (exact time being 7:56) shows that pretty much any method is identicle and only bad thign is too little.

View: https://www.youtube.com/watch?v=r2MEAnZ3swQ
 
Aug 5, 2019
22
3
15
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i mean have you seen kingpins sonic washer?
and der8aur's MB in the dishwasher?




on topic:
the amount needed can vary.

You can watch many tech YT peoples channels and see the typical pea sized "can" be bad ta times (uneven pressure can force more to 1 side than other and you have a corner not covered).

tbh there is never really "too much" (within reason ofc) as excess will be squished out.
Full coverage is your goal (and why some ppl actually spread it over entire IHS for assurance). Just do it slow and little mixing as possible (to not trap large air bubbles...tiny ones have nearly no issue on performance as ppl have tested it)


also depending on the CPU model the makers have their own "rules"

like how with TR its an x with 4 dots between each line, skylake's midle line and corner dots, etc

also this vid (exact time being 7:56) shows that pretty much any method is identicle and only bad thign is too little.

View: https://www.youtube.com/watch?v=r2MEAnZ3swQ
Thanks for the detailed response i appreciate it a ton
 

britechguy

Notable
Jul 2, 2019
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When someone uses the phrase "swapping out" I don't presume that everything can be conveniently removed and placed in dedicated cleaning equipment. Very often that's absolutely not the case.

I will not argue that my way is the only way or the right way, but it is a way that has worked for me. If others choose to apply to the CPU rather than the heat sink, more power to them. Both ways can work.

Provided one applies a reasonable amount, and is careful about seating the items in question, this is not rocket science. It's like squishing denture adhesive on a smaller scale.
 

Tritous

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Apr 3, 2013
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The answer isn't simple, but the reasoning behind it is.

The rule for heatsinks is you want as much heat from the CPU leaving the CPU as possible. the heatsink, heat pipes, fins, airflow...is all about cooling down the main block of the heatsink as it takes heat from the CPU. The Thermal paste is trying to minimise the thermal resistance to that heat transfer.

Thermal pastes (like anything) are not perfect conductors of heat. They are simply better than air. The real goal is to displace the air and make sure there is only paste between the heat spreader of the CPU and the heatsink. I.e. the only job of the paste is to smooth out the imperfection of the CPU to heatsink interaction. The thicker the heatsink the more of a barrier it forms so the goal is the absolute minimum possible paste while still forming an air free layer between the heatsink and the CPU.

Where to apply it...as a rule I find the CPU is a smaller surface than the block so if you cover the surface of the CPU you will get the most coverage. I tend to spread it as thin as possible without being able to see through the paste, covering the whole CPU as the integrated heat spreaders will still transfer heat to the cooler even where it is not over the silicon die itself.

I also pay for good paste. not all paste is equal. They have different temperature ranges (but most cover general use), different burn in temperature (again, usually not a problem), they have different viscosities (big difference in how easy to apply it is), and different thermal coefficients. get the highest coefficient with lowest viscosity which covers your temperature range and which you can reach for a burning (e.g. run a stress test). Spread it fairly thin, make sure there is good pressure from the heatsink and generally that gets the thinnest, most consistent application.
 

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