HS - Matt Black or mirror finish?

[robbo]

Hey,
This is my first post here. Greetings from Australia!
I've been into PC's for years but only recently got into OCing.
If this question has been covered before or the answer is somewhere else then forgive me....
I've been reading a lot about lapping your HS and how this will give you better contact between your chip and the heatsink, and therefore better themal conductivity.
Thing is I remember doing an experiment in a science lesson years ago when I was at school. This experiment proved that the BEST themal absorbing and dissapating colour was MATT BLACK! The WORST themal absorbing and dissapating colour was a POLISHED SURFACE!
If this is correct then why are we lapping our HS to make them as shiny as possible? Surely the HS would absorb heat from the chip more efficiently if the bottom of the HS was matt black!?
So, lap the HS to get good contact and then make it black somehow?!?!?

Am I going crazy? HS of all types where always matt black all over for this reason. Why are we now getting shiny ones?

Thanks for reading! ;)

[silenze]

http://www.a1-electronics.net/Heatsinks/2004/MattBlack_Feb.shtml

8)

[DaMiEn]

I think you're missing the point of lapping the heatsink base. the reason isn't to make it shiney, it's to make it flat so that as much of the heatsink is making direct contact with the cpu die.

Edit: heh 69 posts, nice touch guys 8)

[robbo]

Thanks.
OK that article goes some way to answering my questions, however it's a bit inconclusive.
So, no paint on the fins if they are gonna have a fan to cool them (at anything but low speed setting)
BUT how about matt black paint just on the bottom of the HS?

So, you'd lap your HS for good contact with the die, then spray that contact surface matt black for best heat absorbtion. Science tells us that this should work better than a shiny contact surface. Maybe it makes so little difference that you'd never notice anyway?

PS. Don't worry, I'm not considering spray painting my new HS! It's just the theory that is bugging me.

[undergroundtech]

The composition of the paint will act as a thermal insulator, killing any benefits of having the black color.

[fstroupe]

The answer is in you initial post...the key is contact. Anything you might do to make the surface black will affect the contact.

[T-shirt]

the Matte black is for Radiant heat, since we're hopeing for as close to 100% contact between the HS and the CPU our main transfer will be Conductive.
While having a shiny bottom of the HSF could thoretically reflect back a small amount of heat that is probably minor compared to the insulating affect of any surface coating.
one exception would be Anodized aluminum (anodizing changes/colors a thin layer (a few thounds of an inch at most) of the metal) and many passive electronics heat sink are matte black anodized.

[silenze]

While having a shiny bottom of the HSF could thoretically reflect back a small amount of heat that is probably minor compared to the insulating affect of any surface coating.

Thermal grease.....

[KryoNexus]

I think you're missing the point of lapping the heatsink base. the reason isn't to make it shiney, it's to make it flat so that as much of the heatsink is making direct contact with the cpu die.

Edit: heh 69 posts, nice touch guys 8)

lol, glad you liked it :-)

[playafly187]

hrm... i wonder if you annodized the bottom of the heatsink black, if that would make any difference. im guessing not, as the surface wouldnt be smooth then.

but, if a heatsink could be made with the bottom half of the heatsink a solid blackish aluminum color and the upper half a white color.... :idea:

[undergroundtech]

Actually annodizing acts as an insulator also, just not as bad as other coatings

[GriMo]

it would appear every1 overlooked the fact black absorbs heat from LIGHT better then any other colour...

[wedant01]

Hey,
This is my first post here. Greetings from Australia!
I've been into PC's for years but only recently got into OCing.
If this question has been covered before or the answer is somewhere else then forgive me....
I've been reading a lot about lapping your HS and how this will give you better contact between your chip and the heatsink, and therefore better themal conductivity.
Thing is I remember doing an experiment in a science lesson years ago when I was at school. This experiment proved that the BEST themal absorbing and dissapating colour was MATT BLACK! The WORST themal absorbing and dissapating colour was a POLISHED SURFACE!
If this is correct then why are we lapping our HS to make them as shiny as possible? Surely the HS would absorb heat from the chip more efficiently if the bottom of the HS was matt black!?
So, lap the HS to get good contact and then make it black somehow?!?!?

Am I going crazy? HS of all types where always matt black all over for this reason. Why are we now getting shiny ones?

Thanks for reading! ;)

lol, thats what i though too. but then i thought, having copper out-ways alu with a black finish on contact point

[silenze]

it would appear every1 overlooked the fact black absorbs heat from LIGHT better then any other colour...

Hmm I don't see how that would have an affect either way in this situation..

The fluctuations in the test are just due to the change in the thermal resistance; bare metal surface vs matte black finish surface.. (ya know the medium(paint?) they used to make it black..)

[GriMo]

it would appear every1 overlooked the fact black absorbs heat from LIGHT better then any other colour...

Hmm I don't see how that would have an affect either way in this situation..

The fluctuations in the test are just due to the change in the thermal resistance; bare metal surface vs matte black finish surface.. (ya know the medium(paint?) they used to make it black..)

without a doubt i acknowledge tht paint comes in black. my point however was the COLOUR of the surface is of no relevance. black absorbs heat from light better then a mirrored surface, unless ur CPU is emitting light, {mine doesnt maybe i just have crazy CPU(it is an intel)} the heat threw light absorbtion is irrelevant.. che??? basically what im saying is due to the fact theheat is dissapated in a lightless environment, the colour wont matter at all

[jurtje]

So you don't consider Infra Red to be light then.....
Heat is heat, no matter what the length of their waves is...

[silenze]

it would appear every1 overlooked the fact black absorbs heat from LIGHT better then any other colour...

Hmm I don't see how that would have an affect either way in this situation..

The fluctuations in the test are just due to the change in the thermal resistance; bare metal surface vs matte black finish surface.. (ya know the medium(paint?) they used to make it black..)

without a doubt i acknowledge tht paint comes in black. my point however was the COLOUR of the surface is of no relevance. black absorbs heat from light better then a mirrored surface, unless ur CPU is emitting light, {mine doesnt maybe i just have crazy CPU(it is an intel)} the heat threw light absorbtion is irrelevant.. che??? basically what im saying is due to the fact theheat is dissapated in a lightless environment, the colour wont matter at all

Right, the paint used is the only thing affecting the results.

So you don't consider Infra Red to be light then.....
Heat is heat, no matter what the length of their waves is...

I really don't understand where you're going with that hehe...

[wedant01]

So you don't consider Infra Red to be light then.....
Heat is heat, no matter what the length of their waves is...

yeah your right, he he, i did that stuff 1/2 a year ago lol

[GriMo]

its taken me a while to repsond because ive been trying to find some info as to how much IR is actually emited by a CPU, and cant find anything on it anywhere. i cant imagine it is a huge amount, hoever it would be an interesting experiment, i have an old 1.2 laying around and may be able to run some tests in regards to colours etc, as to what ill use as to clour it im not sure... am thinking a permanent maker or a cd pen. both seem to be thin, and prob wouldnt insulate to much

and yes i now stand corrected, my cpu does emit light, i just cant see it ...

[silenze]

Oh he was talkin' about that.. heh..

Yeah.. most everything emits infrared... but I'm willing to bet white paint would make the same amount of difference in the same test...........

[wedant01]

its taken me a while to repsond because ive been trying to find some info as to how much IR is actually emited by a CPU, and cant find anything on it anywhere. i cant imagine it is a huge amount, hoever it would be an interesting experiment, i have an old 1.2 laying around and may be able to run some tests in regards to colours etc, as to what ill use as to clour it im not sure... am thinking a permanent maker or a cd pen. both seem to be thin, and prob wouldnt insulate to much

and yes i now stand corrected, my cpu does emit light, i just cant see it ...

thats very interesting

[GriMo]

not sure if it still works, its an old hp that has been severly damaged, mobo went bang, replacement was not worth the expense so new pc. ill pick up a cheap board just for the tests and see how diff paints etc will perform. any1 with any thoughts or ideas as to how the test should be run would be great to hear. aka wat materials to apply to the sink, wat colours etc and see what works best. take into account everything else attached to it will be the cheapest i can get/salvage from old boxes( i have a few)

[wedant01]

hmm. well you can try the stock finish, i really shinny finish, a white finish and a black finish.

[GriMo]

update, it would seem that a mirror finish is exceedingly better then any other finish, however one must say that black is much more effective then white. i base this on the fact when using white my p3 became innoperable, to the xtent even with a clean hsf it not longer works. am not sure why, but it was only a folding box so im not concerned.

Stock: 51 (note cracked shitty pad)
mirror: 42
black: 48
white: screwed processor


if my little test proved one thing its painting ur hsf does nothing good. perhaps if there was a better way to coat a hsf it would work better. not sure. in any case ill be sticking to a mirror finish when i get my nice new h20 kit. http://www.swiftnets.com/products/h20-apex.asp<------ looks very tasty, just changing the res is all... wanna clear one. also wonder if a BIX2 would be a better rad.


p.s. you all owe me .4 of a gram of AS5.. hehehehe

[silenze]

I'm not trying to pick on you.
But an analogy for your results:

Car #1 (stock hsf) runs a 13.6 1/4 mile

Car #2 (mirror finish) runs a 10.2 1/4 mile

Car #3 (black matte finish) runs a 11.4 1/4 mile

Car #4 breaks an axle on the hole shot.. didn't get a chance to run, why would you count #2 as the winner over #4 when you didn't even get a chance to see #4 perform..

Shouldn't count it as the definite loser if you didn't get to test it..

[silenze]

"Black objects tend to emit energy very well. This is why we have seen many black coloured heatsinks in the past. That doesn't mean you should go out and paint your heatsink, as this will greatly reduce its effectiveness because the paint will act as an insulator."

Anodizing may yield different results, but like I commented earlier.. the paint itself makes the difference...

[GriMo]

I'm not trying to pick on you.
But an analogy for your results:

Car #1 (stock hsf) runs a 13.6 1/4 mile

Car #2 (mirror finish) runs a 10.2 1/4 mile

Car #3 (black matte finish) runs a 11.4 1/4 mile

Car #4 breaks an axle on the hole shot.. didn't get a chance to run, why would you count #2 as the winner over #4 when you didn't even get a chance to see #4 perform..

Shouldn't count it as the definite loser if you didn't get to test it..

if car 4 has the same axle as the rest, and it breaks where as the rest didn't then yes i would still count it as the loser.

like, all factors where the same, except for the colouring on the hsf. hence if we were testing just the axles in the cars, and the "white" axle was the only one that broke. i would blame the axle.

[silenze]

i base this on the fact when using white my p3 became innoperable, to the xtent even with a clean hsf it not longer works. am not sure why, but it was only a folding box so im not concerned.e

Painting the heatsink white would Not make a big enough difference to have caused damage to your CPU... something else happened....

[FunkZ]

I think the results from the black paint should be proof enough that any coating, regardless of color, is going to have a negative impact on heatsink performance, at least as far as paint is concerned.

As for anodizing, I would tend to think that if it was significantly effective in reducing temperatures that all the big guys would be doing it,... Thermalright, Thermaltake, Zalman, etc. and I haven't seen black anodized CPU heatsinks in many, many years. Hrm, okay well my Volcano 7 was blue, but the copper insert that actually touched the CPU core was bare metal.

I think some of the copper-base heatsinks lately have been nickel-plated, but I'm not sure if this is designed to be a performance enhancer, a corrosion inhibitor or simply for aesthetics.

[XyBeRz]

I've been reading this post and all I can say is that, well at least from my own theories, any kind of paint on the surface that contacts the CPU, whether anodized or painted on will be worse.

True lapping is so that you will get the absolute flattest surface to contact the CPU die as to absorb as much heat as possible.

As for the CPU emmitting IR heat, I dunno, but i know my CPU emits heat, and lots of it. It seems to me that it would be obvious that adding anything other than thermal grease to the bottom of my block would be worse, no matter how thin it is applied on.

True, black absorbs light better than a reflective surface, but that's light. I don't think there would be any type of light between my CPU and the heat sink so I highly doubt that would be of any signifigance.

This is just my theory though, I'm not a scientist or anything near that, just using my common sense and what little bit of knowledge I have picked up from school.