I dunno if this hase been posted or not, and I feel that I should ask before I do anything to the sink.
The heatsink I have right now has these really fine grooves on the base of the whole heatsink which seem to be very nicely polished. Now everyone had said lap the sink for better temperature, but what about these grooves that seem to be very smooth? Would the grooves not increase surface area and increase heat transfer? Or would a absolutely flat and smooth base be better? Some one please enlighten me.
Heatsink base, polished grooves or smooth?
Moderators: NeilBlanchard, Ralf Hutter, sthayashi, Lawrence Lee
Re: Heatsink base, polished grooves or smooth?
Polishing heatsinks has close to no effect, thats my guss, there will always be micocopic holes all over thats not filled, with polishing you risk not making the surface level, which should be a much bigger problem.EvoFire wrote:I dunno if this hase been posted or not, and I feel that I should ask before I do anything to the sink.
The heatsink I have right now has these really fine grooves on the base of the whole heatsink which seem to be very nicely polished. Now everyone had said lap the sink for better temperature, but what about these grooves that seem to be very smooth? Would the grooves not increase surface area and increase heat transfer? Or would a absolutely flat and smooth base be better? Some one please enlighten me.
AtW
I thought there has been tests conducted with lapping (polishing to make flat) the heatsink bases? I recall reading that it made a difference, but I couldn't help feeling that the author started off wanting to prove that it makes a difference...
I think lapping does make a difference, if done properly. Doing it properly is non trivial. And the difference with a god heat sink is minor. I wouldn't go through all that trouble for 1-2 degrees C (if that) of difference. But if you feel so inclined, google "lapping" and I'm sure you'd come up with a whole bunch of instructions. Just be prepared to trash the heatsink if lapping doesn't go well.
I think lapping does make a difference, if done properly. Doing it properly is non trivial. And the difference with a god heat sink is minor. I wouldn't go through all that trouble for 1-2 degrees C (if that) of difference. But if you feel so inclined, google "lapping" and I'm sure you'd come up with a whole bunch of instructions. Just be prepared to trash the heatsink if lapping doesn't go well.
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frankgehry
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- Joined: Sun Dec 12, 2004 5:00 am
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Of course its already been posted. It should be flat but it doesn't have to have a mirror finish. Look at the www.frostytech.com testing procedures.
http://www.frostytech.com/testmethod.cfm
http://www.frostytech.com/testmethod.cfm
Are you referring to the Arctic Cooling heatsinks? I notice that their base is kinda rough - you can feel it with your nails.
My thoughts on this, not necessarily correct, is a flat surface is better. Reasons:
1. A flat surface will provide maximum contact between the two metallic contacts.
2. Thermal compound is used to bridge the gaps where contact is not perfect.
3. Having grooves that need to be filled with thermal compound degrades heat transfer. You don't get more surface area unless you have a perfectly matching set of grooves on the CPU.
My thoughts on this, not necessarily correct, is a flat surface is better. Reasons:
1. A flat surface will provide maximum contact between the two metallic contacts.
2. Thermal compound is used to bridge the gaps where contact is not perfect.
3. Having grooves that need to be filled with thermal compound degrades heat transfer. You don't get more surface area unless you have a perfectly matching set of grooves on the CPU.
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frankgehry
- Posts: 1424
- Joined: Sun Dec 12, 2004 5:00 am
- Location: New York, NY
This is the link I meant to give you. http://www.frostytech.com/articleview.c ... 572&page=4
absolutely flat base vs base with uniform grooves?
It should be flat as determined by a machinist square or drafting triangle. Grooves do not help, but are an artifact of the machining process. The TIM can fill small groves and imperfections assuring there are no air gaps if applied correctly. Center contact with the cpu is most important as that's where most of the heat is transferred. You describe well finished fine grooves.
That sounds ok but does that mean like the fine grooves on a thermalright or a swiftech. Nickel plated or copper. The link has a surface comparator where you should be able to find something similar to yours.
EDIT: All beginners want to lap their heatsinks including myself. If its an old heatsink and has lots of scratches, maybe, but generally don't worry about it as long as its flat. If its new and seems warped or damaged have it replaced. Chances are if you lap it you'll only make it worse.
absolutely flat base vs base with uniform grooves?
It should be flat as determined by a machinist square or drafting triangle. Grooves do not help, but are an artifact of the machining process. The TIM can fill small groves and imperfections assuring there are no air gaps if applied correctly. Center contact with the cpu is most important as that's where most of the heat is transferred. You describe well finished fine grooves.
That sounds ok but does that mean like the fine grooves on a thermalright or a swiftech. Nickel plated or copper. The link has a surface comparator where you should be able to find something similar to yours.
EDIT: All beginners want to lap their heatsinks including myself. If its an old heatsink and has lots of scratches, maybe, but generally don't worry about it as long as its flat. If its new and seems warped or damaged have it replaced. Chances are if you lap it you'll only make it worse.
Ah, I was referring to the metal heat spreader on P4 / AMD64. Bad assumption on my part. CPU is of course siliconEvoFire wrote:1 Isn't the CPU ceramic or something?
3 Really? I didn't know compound degrades transfer, I though it was just used to fill gaps. I did know as least as possible is the best.
I have no idea what's that material on top of the CPU. You're probably right about it being ceramic.Still, my reasoning is that direct contact between two surfaces will result in best transfer of heat. Having thermal compound in between is preferable to having air, but not as good as having direct contact. Since it is impossible to have perfect contact between two surfaces, we use thermal compound. But we use as little as necessary. Having grooves that require (relatively) a lot of thermal compound to fill is not optimal.
In the grand scheme of things:
Pefectly flat, perfectly smooth HS base meeting perfectly flat, perfectly smooth CPU may be the "ideal" situation. But flat is much more important than smooth. If the base is flat, I wouldn't worry about its smoothness unless it was so bad that you can easily feel the individual grooves with your fingernail.
Unless you're very careful, you're more likely to make things worse instead of better when trying to lap a heatsink, by making the base smooth, but concave or convex.
Pefectly flat, perfectly smooth HS base meeting perfectly flat, perfectly smooth CPU may be the "ideal" situation. But flat is much more important than smooth. If the base is flat, I wouldn't worry about its smoothness unless it was so bad that you can easily feel the individual grooves with your fingernail.
Unless you're very careful, you're more likely to make things worse instead of better when trying to lap a heatsink, by making the base smooth, but concave or convex.
My old Taisol sink came with quite a marked grooving pattern from its machining; the sinks had a very good reputation but it did worry me a bit. I lapped it, but as a lab metallurgist I was polishing steel samples every day for microscopic examination, scratch-free at 400x.
If you do decide to lap, get a piece of plate glass to fasten the wet & dry to, keep it wet, start on 240, then 400, and don't bother going finer than 600.
And take it slow & steady, bend the elbow not the wrist. Fast = rocking and curvature.
If you do decide to lap, get a piece of plate glass to fasten the wet & dry to, keep it wet, start on 240, then 400, and don't bother going finer than 600.
And take it slow & steady, bend the elbow not the wrist. Fast = rocking and curvature.
I dunno now, I will have to get a tube of heat transfer material first.... I'm out after redoing the videocard and CPU a month ago
cpemma: that is the simplest lapping method I have seen, will try soon as I have 220, 400, and 600 sheets at home.
Rusty075: that would be too bad... I would have wished for some good comparison... Oh wellz....
cpemma: that is the simplest lapping method I have seen, will try soon as I have 220, 400, and 600 sheets at home.
Rusty075: that would be too bad... I would have wished for some good comparison... Oh wellz....