[Alien]

You know how in reviews of HSFs they tend to consider a smooth, shiny finish to the base of the heat sink to be a Good Thing™? Well I was just wondering if those of you with some experience in the matter think I've managed to get mine shiny enough....



PS - no sanding, or "lapping", or solvents, or polishing compounds were involved, & it came with some of that "chewing gum" type stuff on it....

[felix]

You want a heatsink to absorb the heat, yes?

Let's firstly think about the strip heater in your bathroom.
The silver backing plate is smooth, flat and silver. This silver backing then REFLECTS the heat, and absorbs as little as possible.

Thus, if your heatsink is flat, smooth and shiny it is not absorbing the maximum amount of heat and is actually refelecting heat back into your processor, chipset etc.

Like sound or light, heat is best absorbed by rough, non-reflective surfaces. Thus a heatsink that is black and rough would absorb more heat than a shiny silver smooth heatsink as long as you remove air pockets. You want your heatsink to absorb the heat, not reflect it back on the processor.

Also, a rough surface has a greater surface area than a smooth one, meaning that there is more contact between the heat transfer compound and the heatsink.

Think about this for a while.
Take care,
Felix.

[Dirty Harry]

NO, NO, NO

Are you trolling ?

What you say about a rough black surface absorbing heat is only true when you talk about radiating heat, like collecting heat from the sun or radiating heat from a heating element.

Basic school physics already teach that heat can be moved in three ways, transferring (like pouring hot water into cold), radiated (=adsorbed on the receiving end) and conducted. Conduction is much more effective than radiation and the color is irrelevant for this. To conduct heat the contact is essential, the better the contact is the better heat gets conducted. Opposite, when you insulate something you put a layer in between that conducts poorly (like air).

A heatsink is conducting heat from the CPU and radiating it from the fins on top. In order for it to conduct heat from the CPU the best thing is to have as perfect contact as possible. That's why you want the bottom of the heatsink should be perfectly smooth, and the contact ensured with paste (preferrably Arctic Silver)

H.

[Alien]

Felix - it wasn't an entirely serious question - I know that the bases of heat sinks are supposed to be nice & smooth & shiny [as shininess is an indication of how smooth/flat it is]. Basically I was trying to bait ppl's curiosity & see if they could guess how I managed to get rid of the gunk that came with it & get the place where the gunk was as shiny as the surrounding area without using any of the methods I mentioned.

[Dirty Harry]

So tell us !
H

[Bursar]

I suspect it was something like this which I did a while ago: http://www.philspcmods.com/modules.php?o...le&artid=10

Ah, just read your post again, and I missed the bottom bit. Never mind.

And how does something being shiny relate to it's ability to being flat?

[Dirty Harry]

Quote:

And how does something being shiny relate to it's ability to being flat?

It doesn't necessarely, but if its hiny you can see the scratches. Besides, metall tends to become shiny when you polish the roughnesss away...
Of course if its uneven, or rough, it doesn't matter if its shines or not.

H.

[Alien]

Quote:

So tell us !
H

's quite simple really - remove the fan, put heat sink in a sealed/air-tight plastic bag, then place it in freezer for about 2 or 3 hours. When you take it out just use your fingernails to pick off the now brittle "chewing gum". After that I just buffed it with kitchen roll. They'd made the base nice & shiny, but I was really surprised & pleased that I managed to get the bit where the "chewing gum"had been as shiny & clean as the surrounding area.

[Bursar]

So your heatsink isn't neccessarily flat then, it's just shiny. ;(

[Alien]

It's shiny & flat as far as I could see - I could detect no curve to the base, as I have read about in some HSF reviews, though there was a slight amount of machining marks visible, hence the distortion in the reflection.

[Marktait]

So what did you get out of it being flat, was it worth while?

Did you see much of a difference in the temperature of the CPU?

[Alien]

I wouldn't know - I cleaned the "chewing gum" off of it dtraight away, before using it. I wasn't the 1 who made it flat, whoever made the heat sink did that. But getting the "chewing gum" off of it & replacing it with Arctic Silver should have made a bit of a difference compared to how it would have been if I'd just used the stuff they put on it. Also, if you clean that gunk off with something like isopropyl alchohol, or some other solvent, chances are that you won't get it all off, & it's possible that that could interfere with the heat transfer.

@ the end of the day I want to do as much as I can to keep both my system & CPU cool. I would like to be able to overclock my system, but there's no way I'm gonna attempt it with my idle temps @ what they are @ the mo [varies from about 46&degC to 52&degC, depending on room temp].

I do have some more work to do on my case, which should hopefully improve temps, like increasing the number of front case fans from 1x80mm to 2x80mm + 2x60mm [there isn't enough room to put 4x80mm in without ruining the look of the case]. I'm also thinking of replacing my rear 92mm fan with a 50cfm 1.

[Dirty Harry]

[Alien]

I'm running an XP1900+ @ its stock speed of 1.6Ghz. I'd like to get my maximum idle temp down to the mid 40s or lower before I try upping the FSB, or fiddling with any other performance-related BIOS settings.

Also, I'd like to solve the prob with my sound card before I risk doing anything that might make it worse.

Oh, & 46&degC is only when my room temp is really cool - during the day it [CPU] stays around the 50-52&degC mark. @ the moment it's @ 48&degC, but my system temp is only 27&degC.