Lapping FTW

[lee63]

I think I finished mine off with 2000 grit.... looked like a mirror.

[Bman212121]

Originally Posted by ViN86

if this is the case then you were using too much TIM.

transport fundamentals says a higher grit (smoother) flat finish will have better contact and better heat transfer.

I'd also say it could have to do with what type of TIM you're using. If your TIM is too thick that it cannot stay in the holes I'd try some different stuff. Using Zalman STG-1 I can get the paste incredibly thin and still have full contact.

@mailman2: Nope I definitely haven't been lapping procs very long. But I'm still going to argue that I could achieve better results from a smoother finish. I have a few ideas to test my theory with.

[ViN86]

Originally Posted by Bman212121

I'd also say it could have to do with what type of TIM you're using. If your TIM is too thick that it cannot stay in the holes I'd try some different stuff. Using Zalman STG-1 I can get the paste incredibly thin and still have full contact.

@mailman2: Nope I definitely haven't been lapping procs very long. But I'm still going to argue that I could achieve better results from a smoother finish. I have a few ideas to test my theory with.

the only theory you need is that

heat flux = driving force / resistance

resistance = sum of individual resistances
driving force = difference in temperature

heat flux (aka heat removal) is higher for direct contact than it is with TIM in the interface (which is an extra resistance term). so a smoother finish increases contact and minimizes TIM resistance, hence better heat transfer.

transport fundamentals 101...

this also explains why you cant cool something below ambient temperatures without doing work.

[Bman212121]

Originally Posted by ViN86

the only theory you need is that

heat flux = driving force / resistance

resistance = sum of individual resistances
driving force = difference in temperature

heat flux (aka heat removal) is higher for direct contact than it is with TIM in the interface (which is an extra resistance term). so a smoother finish increases contact and minimizes TIM resistance, hence better heat transfer.

transport fundamentals 101...

this also explains why you cant cool something below ambient temperatures without doing work.

Well I can understand his POV, and can back it up with what you're talking about. Let's say I have a rougher surface that is completely filled with TIM and makes a solid bond between the two metals. It won't be as effective as having a solid piece of copper. Now if in his instance the force of gravity plus heat causes the liquid to flow downward, the seal of the liquid could potentially create a vacuum that would suck all of the TIM out from in between the two materials causing air to be trapped in between the two metals. (Just throwing out some type of example, doesn't really need to explain how) This would probably be lower exchange because air is even worse for heat transfer. You'd basically have air pockets because the TIM can't get into the even smaller holes.

My logic is just like yours Vin that if you actually have a flat smooth surface and not just a shiny surface then you should have superior heat transfer with little to no TIM. One of the things that is going to effect how well you can accomplish a good bond is the type of mounting brackets you're using. The flatter the surface the more susceptible it is going to be to jarring. One thing about the TIM running scenario that doesn't make sense to me is that you'd think both pieces of copper should in fact be touching in many locations, essentially creating a seal around the TIM not allowing to just run off. I'm not saying that it isn't feasible, but I'd guess there are ways to work around that issue so it doesn't happen.

[mailman2]

Originally Posted by ViN86

if this is the case then you were using too much TIM.

transport fundamentals says a higher grit (smoother) flat finish will have better contact and better heat transfer.

No, it wasnt too much. I use the slightest dab. AS5 performs best for me even though I've got tubes of all the top performing TIM here. AS5 has always given me the best results and the best overclocks. I use as little as possible because my water block and CPUs have a perfect mating.

Sorry but therories are out the door when real world testing of a CPU / Lapping / TIM application are applied. I have done extensive testing, the TIM sets better with less than mirror finish resulting in slightly better temps. You can argue all your want but I've got hours of testing that prove otherwise.

[ViN86]

Originally Posted by mailman2

No, it wasnt too much. I use the slightest dab. AS5 performs best for me even though I've got tubes of all the top performing TIM here. AS5 has always given me the best results and the best overclocks. I use as little as possible because my water block and CPUs have a perfect mating.

Sorry but therories are out the door when real world testing of a CPU / Lapping / TIM application are applied. I have done extensive testing, the TIM sets better with less than mirror finish resulting in slightly better temps. You can argue all your want but I've got hours of testing that prove otherwise.

LOL theories are out the door huh? tell that to the numerous industries that use these LAWS to model their system.

your hours of testing are all fine and dandy, but something is not the way we are assuming it is if the data doesnt agree with the funamental basics.

[wysiwyg]

i got my Q6600 to 3.5 without lapping it, but good one reaching 4

[FastRedPonyCar]

This is what my Zalman looked like right out of the box.

[bob saget]

wow.

[hokeyplyr48]

holy.... thats ridiculous!

[crainger]

Yeah, Zalman always have really shiny surfaces. My Zalman waterblock was like a mirror. The problem is, is it really lapped? or is it just a coating to make the finish please, while at the same time actually being a small hinderance?

[mullet]

Yeah Zalman has there stuff together.