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painting your heatsink black make it run cooler TESTED - XFX R9 290 heat sink paint job

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Please refrain from bumping or necroing old threads. 

 

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!!THE THERMAL TESTS ARE DOWN BELOW THE PICTURES!!

 

The XFX r9 290 is a really beautiful card, but the fact that the heat sink isn't nickel plated and you can see the raw copper heat pipes drove me nuts. That’s why I just had to do something about it.

 

So due to my white "case" I decided to paint it white. I used a normal matt white nitrocellulose spray can. I choose nitrocellulose spray because I hope if I ever want to get rid of the paint that I just have to lay it in a nitrous bath to dissolve it. 

Sadly the paint job didn't turn out perfect. I used an air compressor to dust off the heat sink, but apparently there was still dust on it, so I had to pick the dust particles, which were lying across the fins, with a fine pair of tweezers (worked astoundingly well).

 

Final results:

 

post-61013-0-20046900-1421511418_thumb.j

post-61013-0-56119700-1421511454_thumb.j

 

 

post-61013-0-38430900-1421511515_thumb.j

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Heat sink before I picked the dust with tweezers:

 

post-61013-0-50261700-1421511566_thumb.j

post-61013-0-43755500-1421511570_thumb.j

 

 

post-61013-0-30493900-1421511576_thumb.j

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After I picked the dust:

 

post-61013-0-85782100-1421511713_thumb.j

 

Back in my rig. The white is not as bright as in the picture in real life:

 

post-61013-0-94822000-1421512689_thumb.j

 

 

Thermal test:

 

I read in a forum that painting your heat sink black would make it way more efficient because of the effect of heat radiation. If that is true it would mean painting your heat sink white would make it way worse! I didn’t believe it for a couple of reasons.

 

White has a heat reflection coefficient of 1 and an absorption coefficient of 0, which means that a perfect white would reflect all radiation heat it encounters, so it should make the heat dissipation via radiation on the cooler a lot worse. BUT this also means that all the radiation heat from other components gets reflected and could mean lower temperatures.

Black has a reflection coefficient of 0 but an absorption coefficient of 1, which means, it can exchange heat via radiation a lot better but also absorbs a Lot more heat.

In reality a the heat sink of a single GPU set up doesn't get a lot radiation from other components, but most importantly a heat sink is designed to exchange heat via convection and just a fraction is exchanged via radiation.

 

My Test:

 

I set my GPU fan speed in both tests to a static 50% and let it run valley for half an hour. My card was not overclocked and ran factory settings.

 

1 test with normal heat sink I got an average of 79 °C:

 

post-61013-0-13918300-1421514819.png

 

2 test with painted heat sink I got an average of 89°C:

 

post-61013-0-58041200-1421515012.png

 

I was really shocked by the massive 10°C difference and started believing the myth, so I tried remounting the cooling unit, but same result (I used stock thermal paste in the first test and Noctua NT-H1 in the second). 

 

So what caused the increase in temperature?

 

I am not entirely sure.  I was so stupid and did just do one test, with only one fan speed, on the stock card and forgot to change the thermal paste which could make a difference as well. If I would have made several tests with multiple fan speeds I could discern how big of a role heat radiation is playing in the heat exchange process.

Also a factor for the heat increase could be the added layer of paint. Before the heat can get carried away from the air it has to go through the layer of paint, instead of getting carried away from the aluminum instantly. The paint is a plastic which has a very low heat conduction coefficient and acts like heat isolator (plastics such as paint have a λ between 0.17 and 0.24 W/(m · K),  pure aluminum λ of 236 W/(m · K) ). This applies for paint in general not only white paint.

 

Conclusion:

 

My conclusion is that it has to be a combination between the radiation and the bad heat conduction, because I just can't believe that a 10°C could come from heat radiation only.  

 

Does this mean painting your heat sink black makes your GPU/CPU run cooler?

 

Maybe!

 

Even if my results might make you believe so, I honestly can’t tell from this test, because I can’t discern what made my GPU run hotter. It could go either way, dependent on the benefit of radiation outperforming the disadvantage of the heat conduction 

 

To Note:

 

My results are not reputable at all, I did do too less runs and had too much variant between the runs, like the thermal paste, but I am very hooked now. I really would like to get some CPU air coolers and test this again with white, black painted and white, black anodized (to remove the isolation effect) and with different fan speeds to really get some nice results. If I find a cheap way to do it, you will definitely hear from me again ;)

 

Please post your comments and criticism down below

post-61013-0-20046900-1421511418_thumb.j

post-61013-0-56119700-1421511454_thumb.j

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post-61013-0-50261700-1421511566_thumb.j

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post-61013-0-30493900-1421511576_thumb.j

post-61013-0-21308100-1421511581_thumb.j

post-61013-0-70792500-1421511647_thumb.j

post-61013-0-38422500-1421511651_thumb.j

post-61013-0-85782100-1421511713_thumb.j

post-61013-0-94822000-1421512689_thumb.j

post-61013-0-13918300-1421514819.png

post-61013-0-58041200-1421515012.png

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It looks pretty, but I think you forgot that although the paint is white, you also painted over the materials that dissipate the heat, effectively covering your heatsink in a sexy white fleece blanket.

 

EDIT: I think the only way you could paint the heatsink without a negative performance impact would be to anodize it, but I'm not 100% sure on that one.

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The paint doesn't transfer heat as good as metal.

This means that you have practically covered your heatsink in a blanket, just as tmcclelland455 described it.

When in doubt: C4

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The paint doesn't transfer heat as good as metal.

This means that you have practically covered your heatsink in a blanket, just as tmcclelland455 described it.

 

Yes absolutely right . I tried to explain this with:

.

 

So what caused the increase in temperature?

 

I am not entirely sure.  I was so stupid and did just do one test, with only one fan speed, on the stock card and forgot to change the thermal paste which could make a difference as well. If I would have made several tests with multiple fan speeds I could discern how big of a role heat radiation is playing in the heat exchange process.

Also a factor for the heat increase could be the added layer of paint. Before the heat can get carried away from the air it has to go through the layer of paint, instead of getting carried away from the aluminum instantly. The paint is a plastic which has a very low heat conduction coefficient and acts like heat isolator (plastics such as paint have a λ between 0.17 and 0.24 W/(m · K),  pure aluminum λ of 236 W/(m · K) ). This applies for paint in general not only white paint.

 

 

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I'm confused, the title says painting black? I'm 99.9999% sure if you painted it black the results would be identical btw.

 

 

If you were to lightly dust it with paint, you'd nearly achieve the same visual appearance without hurting performance so much. This is what they do with radiators.

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  • 4 months later...

I'm confused, the title says painting black? I'm 99.9999% sure if you painted it black the results would be identical btw.

 

 

If you were to lightly dust it with paint, you'd nearly achieve the same visual appearance without hurting performance so much. This is what they do with radiators.

i know i'm a few months late (was searching how to keep my GPU cooler) but it's actually proven that if it's painted black it is better at dissipating heat, they do it with car intercoolers, someone tested it with a box fan and got almost a 25C difference on quite a small one, so it should be relatively the same on a heatsink.

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- snip -

 

Black anodized heat sinks works ~10% better compared to blank aluminum once using natural convection. That's why I only use black heat sinks for my fanless designs.

However the addtional layer of plastic paint is an awful isolation and will erase every positive effect. It is important to keep the paint layer as thin as possible.

Mineral oil and 40 kg aluminium heat sinks are a perfect combination: 73 cores and a Titan X, Twenty Thousand Leagues Under the Oil

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  • 3 years later...

WRONG!!!  Sorry (not sorry) c'mon guys!!  This is physics 101! You SHOULD know this stuff particularly before touting the 'knowledge' you possess as fact.  I despise the spread of bad information because it creates dumb, complacent people and that helps none of us. 

 

That said, I realize this is an old thread but there is obviously some confusion about some very basic principles of physics in this thread and i am compelled to chime in with knowledge proper. 

It doesn't matter the color you choose... unless you use a paint or coating that contains a considerable amount of metal or other additive that is VERY good at conducting heat, painting a heat sink will render that heat sink less effective.  Period.  Why?  Paint covers the interface between the aluminum and the air.  This is where heat transfers away from the aluminum and is absorbed by the surrounding air molecules. It's adding a layer of insulation to the system and reduces the overall ability to move the heat away from the source.  Painting a heat sink is the exact wrong thing to do. 

The two post before this one are wrong... the following article and video explain why... knowledge is free... understand it... THEN share.  ✌

AutoEvolution.com - ARTICLE - Does painting your intercooler black make it more efficient???

 

VIDEO - Black Painted Intercoolers - Myth Busted

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