PINOYDSL's Heatsink Lapping Guide

Discussion in 'PC Modifications' started by ojpd, Apr 1, 2007.


  1. ojpd

    ojpd Member




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    PinoyDSL's Heatsink Lapping Guide
    (A.K.A. PinoyGeek's Heatsink Lapping Guide)

    Project Start: March 25, 2007
    Project End: April 01 2007
    By: O.J. P. DueƱas A.K.A. "ojpd"
    ===============================


    First of all I made this guide specifically for enthusiasts and risktakers. For those who are just curious about how it's done I am not in any way encouraging you to this but if you decide to do so bare in mind that you are doing it at your own risk. I will not be blamed for any damage that you may cause to your system if you mess things up.

    WHAT IS HEATSING LAPPING?
    To be short... Heatsink Lapping is a process in which one laps and polishes the aluminum or copper surface of the heatsink until it reaches a "mirror like" finish.


    WHY DO SOME PEOPLE LAP THEIR HEATSINKS?
    Usually the stock Heatsink or in some cases even aftermarket heatsinks are not properly finished in the factory which then gives tiny holes/ unevenness on the bottom surface of the heatsink that comes in contact with cpu.

    These "tiny holes" / uneveness / scratches / lines become air pockets if the PC is on where in the processor gets hot and instead of the heat travelling directly to the heatsink these tiny holes/uneveness instead trap hot air which then causes less heat dissipitation which then yields a hotter cpu.

    If you own an Athlon64 cpu retail heatsink try to feel the bottom surface of the alluminum heatsink so you will know what I'm talking about. Lots and lots of circular lines Right?

    now... on to the guide.

    WHAT DO YOU NEED?

    1. A HEATSINK (D O H)

    [​IMG]

    I used this.. An old thermaltake Venus 12 HSF that was lying around in my room. Don't get me wrong the Venus 12 is an awesome HSF already but for the benefit of the PinoyDSL and PinoyGEEK community let's lap it.

    First thing I had to do was check the idle and load temperature of the PC using the unlapped heatsink. I couldnt think of any benchmark so I just measured idle temp and load temp while encoding a dvd. More on this later.

    So after 2 days of monitoring the temps. It was time to start lapping. I removed the fan and the lock that was attached to the heatsink. A fairly easy task that doesn't need pics or more explaining to do. If you can't figure out how to remove the fan from a stock AMD or Intel heatsink STOP NOW.

    [​IMG]

    Here's a pic of the naked HSF. Looks smoother than a stock Athlon64 heatsink but it's not smooth enough because when you use a magnifying glass to check the surface out you can still see the tiny pecks on the surface.

    2. SANDPAPER -ers

    Bare in mind that when you buy your sandpaper from Ace Hardware or Handyman kindly tell the bagger boy/lady not to fold or bend the sandpapers. You need them to be as flat as possible.

    400 grit
    [​IMG]


    600 grit
    [​IMG]


    800 grit
    [​IMG]


    1200 grit
    [​IMG]


    2000 grit
    [​IMG]

    Usually it would require a 1500 grit sandpaper but since I am lapping a smoother Venus 12 HSF instead of a stock HSF I skipped the 1500 grit and went directly to 2000 grit.


    3. TAPE (any kind will do)

    I used these
    [​IMG]


    4. A PORTABLE FLAT SURFACE (A wide flat book will do)
    [​IMG]
    Of course you can use books from other authors! Heller? lol


    5. A FLAT PIECE OF GLASS (I used a picture frame's glass)
    [​IMG]
    The Flat piece of glass must fit or be proportionate in size with your portable flat surface. In this pic I already the attached the sandpaper to the glass.

    6. A Flat working space (I used the bar in my room)
    [​IMG]

    7. PURE Isoprophyl Alcohol (The one that doesnt have moisturizer or cologne)

    DO YOU REALLY NEED A PICTURE?

    8. Some water

    DO YOU REALLY NEED A PICTURE?

    9. A little powdered detergent (Optional)

    DO YOU REALLY NEED A PICTURE?


    WHAT TO DO?

    Take your 400 grit sandpaper and tape it's back to your flat piece of glass.

    FRONT
    [​IMG]
    Here you can see I put some tape on top and on the bottom part. Put some tape on both sides as well and make sure that your sandpaper is tightly mounted on your flat piece of glass.

    BACK
    [​IMG]
    You will be repeating this process with your 600, 800, 1200, 1500 and 2000 grit sandpaper after you're done lapping with you 400 grit.

    Atlast...

    LAPPING

    1. Bring all the materials you need and go to your working area.

    2. Place your mounted sandpaper+glass on top of your portable flat surface (book) and place your portable flat surface (book) on top of your flat working space (bar surface)

    3. Place your heatsink bottom surface facing down on the center of your sandpaper+glass and gently start pushing up and down. Let the heatsink carry it's own weight. You may add a little downforce but be careful not to place too much. Bare in mind that in this guide "LITTLE" really means little.

    4. Take note of how many pushing UPs and pulling DOWNs you have done. EX. 60 Ups and Downs. In my case I maintained a medium speed-steady pace for 4-5 minutes. After you've reached 60 ups and downs (4-5 minutes) twist the heatsink 90 degrees clockwise and repeat the process.

    MAKE SURE THE WHOLE SURFACE OF THE BASE OF THE HEATSINK IS TOUCHING THE SURFACE OF THE SANDPAPER WHILE YOU ARE PUSHING UP AND DOWN.

    5. After a full 360 turn of the heatsink try to feel the surface. Check it if you can still see any obvious physical uneveness. If don't see any it's time to switch to the 600 grit. You will be doing the same process and you will only be doing it until you stop seeing the marks left by the 400 grit process.

    This is how you do it...
    [​IMG]

    6. After seeing and feeling that you have a clean and even 600 grit surface do the same using the 800 grit surface switch to the 1200 grit surface and this time start doing it in one direction only. Up and down with a little more downforce and a little more speed but no more 90 degree turns. Again do this for about 5 minutes or until you clearly see that you have a clean 1200grit finish.

    7. Lapping with the 1500grit surface is still just like lapping with the 1200grit surface. Do this a little bit longer.

    MAKE SURE THE WHOLE SURFACE OF THE BASE OF THE HEATSINK IS TOUCHING THE SURFACE OF THE SANDPAPER WHILE YOU ARE PUSHING UP AND DOWN.

    8. Do the same process you did in step 6 and 7 with the 2000 grit surface but this time try to miniimize the downward force. Push up and pull down until the grits on your sandpaper is completely gone. You may also add a couple of drops of water on the center of the sandpaper if you want to.

    9. This isn't recommended but in my opinion it seems to give the surface a little bit more mirror-ish effect. What I did was I tore a piece of the worn out 2000 grit sandpaper and used my index and middle fingers and started lapping the surface of the heatsink in a uber-fast pace but at the same time not exerting any force.

    10. Now you may clean your heatsink with your PURE Isoprophyl Alcohol. BE VERY MODEST.

    11. I also cleaned the old goo off the CPU's surface with Isoprophyl Alcohol and used this as a finishing touch to both CPU and HSF.

    [​IMG]

    PICTURE! PICTURE!

    Mirror Finish (My eyes look very sleepy)
    [​IMG]

    Another Pic
    [​IMG]

    See how the base of the lapped heatsink reflects my guitar's design?
    [​IMG]

    Never use your fingers when monitoring temperatures. I learned the hard way.
    [​IMG]



    A LITTLE TEMPERATURE MONITORING:

    AMD Athlon64 X2 3800
    DFI Mobo
    7900GT
    Geil 2x1GB
    ETC, ETC

    Before Lapping
    39C - Idle
    50C (DVD Encoding)

    After Lapping
    35C - Idle
    46C (DVD Encoding)

    After Lapping + AS5 (3 days curing)
    33C - Idle
    43C - (DVD Encoding)


    CONCLUSION:

    PinoyDSL Rocks! PinoyGeek Rocks! Lapping Rocks! :)


    PS. I'm too sleepy to check for typos so please bare with me. I will polish everything tomorrow.
     
  2. dyoddyowel

    dyoddyowel Member




    very nice guide...

    sticky to dapat...
     
  3. jack11

    jack11 Member




    Di mo na ba kailangan lagyan ng paiste yung paglalapping (yung kulay gray na parang grease)?
     
  4. ojpd

    ojpd Member




    The paste you're talking about is the thermal grease that should be applied on your cpu before you re-mount you lapped heatsink. Right? Di na yun part ng lapping so diko na include... But if you want a suggestion kung anong paste gamitin... I personally use Artic Silver 5.. around P550 price nya.. Read the guide in the AS5 site before applying.

    @dyow

    Tnx bro
     
  5. primus

    primus Member




    4 degrees difference? sure ka ba sa temp readout mo? 4 degrees is a huge jump, usually you can obtain that if you run a water-cooled + lapped heatsink.
     
  6. ojpd

    ojpd Member




    @primus

    Yeps.

    add ko nalang to para hopefully mas lalong klaro sa lahat.

    --A good name brand watercooled hsf is and always will be cooler than an air cooled HSF. Both BEFORE and AFTER lapping. It also produces less noise compared to air cooled hsfs.

    --Provided that it was done properly and patiently.. If there is an expected 3C-5C drop in temps from lapping a once unlapped watercooled hsf with an uneven base there is no reason why we can't expect a 3C-5C drop in temps on an aircooled hsf with an uneven base.

    What causes the drop in temps is the complete elimination of the tiny holes/uneveness aka air packets that trap hot air between the cpu surface and the base of the HSF.

    --People who lap their heatsinks do it because of the fact that there is an expected 3C-5C drop in temps if lapping was done properly. If you look around there are even people seeing as much 6C-7C drops in temps from 12 hour long lap jobs.

    --3C-5C is normal and it will all depend on the kind/model of the HSF you are lapping, how you lap it, how you clean it after lapping, the way you apply thermal grease, how much you use. The key factors are time and patience.

    It will also depend on your complete setup itself, and just like in everything that has to do with desktop computers.. EX same videocard, same mobo, same everything = varying benchmark scores. Or in overclocking...

    (even if you have 2 CPUs of the same stepping.. temps, idle and max load temp, max overclock reached, amount of voltage needed to overclock etc etc.)

    ...RESULTS WILL ALWAYS VARY.
     
  7. primus

    primus Member




    the biggest factor of heat sink is the actual material composition and its density to absorb and dissipate excess heat , I have done a lot of lapping and none of them can reduce the heat of more than 4 degrees, one main reason is lapping will not (per say) reduce the heat it only optimize the contact between the heat sink and the cpu to trap and absorb the heat equally hence it can achieve a better heat dissipation, the actual heat sink has to be designed properly to dissipate the excess heat, every aluminum based heat sink is subject to density, size, composition and conductivity in able to absorb more heat and to dissipate it quickly, not all aluminum can dissipate the heat equally.

    the bottom line is, lapping can only help to equalize the distribution of heat, it is in no way that it can reduce the heat, the entire alum structure, fin design, conductivity, air thermal flow and density is the main key factor for thermal problems.
     
  8. [L]es

    [L]es Member




    good read ! now if only i had the patience.... :)
     
  9. ojpd

    ojpd Member




    I'm with you on this one. But bare in mind that the heatsink used in this guide is not made of al. It also has a high performance fan operating at a little more than 5500 RPM.

    Since you're talking about alum I guess I can agree.

    Too bad it didn't work out for you dude. Bottomline if you insist that a 4C drop ins't possible that's really just because your experience yielded negative results and your opinion is very much accepted.

    However concluding that a 3C-5C drop is impossible is kind of a little too bold since there are countless of other enthusiasts all over the world who achieved positive results. I guess it's really your word against the results of others.. No disrespect. But anyway your word is your word and your opinion is your opinion and nobody can take that away from you.

    Do me a favor though and let's not turn this "guide" into another debate thread. But do know that your opinion coming from your personal experience is and I'm sure will be openly accepted by anybody who reads this guide.
     
  10. primus

    primus Member




    i am not debating about this, it is more of intellectual discussion, we have to make every user who can read this thread to understand that lapping is not the entire solution for decreasing the temperature, you as the author of the guide *must* be clear with the readers that lapping is *only* to optimize the absorption of heat and in no way can be fully use as the best alternative for thermal problems. :)

    back to topic...

    (me and the group who perform thermal design) the way we conduct our test after the lapping is done is, we don't use any fan during the test and we do the test in a controlled environment for an accurate ambient temperature, it is basically a bare heat sink only, then a proper pc based digital thermal meter is use to collect the information required and the behavior of the heat and how it dissipate is carefully studied, by the way, (we do design heat sink for medical,industrial,military purpose only). we don't use the fan because it can interfere with the resistance of the materials under test and fan creates a turbulence that creates an unbalance dissipation of heat. That is the reason why i said i/we can't get a drop of 4c, also i did not say that getting a drop of 4c is impossible, what i said was i could not get a 4c drop on them (unless i use a forced convection or a bigger area/mass to dissipate heat.)

    the best material that can achieve a better heat transfer is the silver or alloy.. it is smaller but same result with a regular heat sink being used, have you noticed the original p4 775 intel heat sink? the plate that actually touching the cpu is made out of silver and the outer fins are made of aluminum...
     
  11. ojpd

    ojpd Member




    Yeah I agree with you. I was focusing more on just describing and explaining how it is done. But anyway I have taken notes from your input and I will try to add them in a couple of days or baka mag tapos nalang ng holyweek.

    Cool.

    Dude I apologize.. Misunderstanding... My bad..
     
  12. primus

    primus Member




    no probs dude!.. hehehe...

    anyway,

    just to help you out on how you can measure the temperature of your system based on some variables.

    i won't go into deep technical details here, the very basic formula is Case Temp. + Heatsink Performance x CPU Dissipation

    most heatsink are rated between 0.5k/w ~ 1.5k/w due to its finite size of the heatsink and its material composition which is always an aluminum.

    let say the CPU can dissipate a 25W of heat and your case ambient temperature is 35 degrees, now let's put them all together here..

    first let's get the CPU temperature, the result here is always higher than the ambient temperature,

    Heat Sink x CPU Dissipation

    0.5 X 25 = 12.5 degrees -> no matter what type of fan you use here and even if you use a 1000 rpm fan here, that is always the CPU temp and its higher than ambient.

    now let's add the ambient temperature which is your case temp and add it to the cpu temp.

    12.5 degrees + 35 degrees = 47.5 degrees <- this is what your heatsink needs to deal with.

    so, as you can see here that having a fast fan does not really cools down your heat sink but rather it is use to convey the heat to the entire heat sink hence the "Forced Convection" a lot of user have a misconception that the primary purpose of the fan is to *cool down* the heat sink and that is entirely wrong.

    now, there's nothing we can do to the CPU temp and the only way you can drop the temperature is by altering the ambient temperature (case temp) if you can drop the case temp it would result to a better reduction of heat, so lapping a heat sink will not reduce the heat, it can only help the cpu to equally distribute the dissipation.

    this formula here is the most basic way of determining your temperature,
     
  13. genemae

    genemae Member




    Maybe primus it would be better and easier rather than lapping.. is to do the opposite.. Increase the contact surface area of the thermal paste by scratching the bottom of the heatsink with some sort of sandpaper while keeping it still flat.. and then use a thermal paste to fill in the gaps crevases of the scratches... this will increase the surface area in contact with the paste..

    this would be in accordance with Furiers Law
    Q=uAdeltaT
    where u is the conductance and A is the surface area... and Q is heat transfer..

    Ano sa tingin mo pre hehehe...
     
  14. primus

    primus Member




    hehehe... thermal paste is only to fill the gaps, the paste is only a medium to transfer the heat to the heat sink, the furiers law is not a formula to reduce heat but a formula to determine the effectiveness of the thermal paste for conductivity and to determine how fast the heat can be transfered equally to the heat sink.
     
  15. ojpd

    ojpd Member




    I really like the way you explain how some of the processes work with good detail.. But If you read the intro I specifically stated that I made this guide for enthusiasts. I think the word itself is definition enough.. If a person is seriously looking into lapping we (or I) should assume that the said person is already aware of the bits and pieces as well as the proper factors and situation that should exist before and after the lapping process.

    I noticed that you used the word "here".. When you say "here" you're talking about the experiments you and your group have done right??? But if you're talking generally then you might wanna double check your group's findings dude. There is a reason why TT includes fan controllers with most of their HSFs. In the model used in this case turning down fan speed at around 2000 rpm will yield an increase in cpu temp but lesser noise. If it is cranked all the way up to 5500rpm cpu temp will decrease but noise will. This btw is also the case BEFORE the HSF was lapped.

    TT is also not the only company who pay extra production costs to include fan controllers with their products. I am hoping that you won't say something like "fan controllers are just there to hype up their products" as I am quite sure the engineers behind TT as well as other good name brands put them there for a reason. I don't wanna go into details dude but fan speed can influence cpu temp...

    On the other hand if what you really meant was "No matter what the speed of your hsf's fan is.. A specific cpu model's max thermal output is constant." then I would agree.

    :shock: Dude all I said was it had a powerful fan spinning at 5500rpm...

    Way out of topic but take the gpu of a videocard for example. Tweakers would go as far as void their warranty and modify their bioses and set their fan speed to max. I don't wanna go into details but obviously this process is being done because of the influence of the speed of the fan in the gpu's temp.

    We can even use ram as an example. Some people would glue or somehow find a way to physically put 2 small fans directly above their ram sinks. It's because these fans blowing towards the sinks can help reduce the temp of the ram's metal sinks.

    Also have you ever tried touching any of your fan robbed heatsinks while your cpu is running large tft prime95 tests? I'm quite sure that even your fingers will feel the difference in temps between an hsf with and an hsf without a 5500rpm fan. Provided that it is sucking in cool air from let say.. A strong side case fan.. A fan will help cool down an HSF.

    Heat transfers from the top surface of the cpu which can also be called a sink itself.. The heat will travel to the HSF... The HSF fan sucking cool outside air (EX. side case fan, top case fan and side case vents) as well as incase air will then be blown towards the HSF.. Seriously dude you really don't think that a fan can help cool down a heatsink??

    1. If you take a heatsink that comes stock with a fan and then you remove the fan... You turn on your PC... You run a couple of torture tests while checking cpu diode temp as well as feeling it with your fingers...

    2. You then turn off your PC and attach a fan.. Let's say.. A 5000rpm fan.. You run the same tests while checking cpu diode temp and feel it with your fingers again.. It would most likely be experiment number 2 that will yield a lower temp result.

    Excellent input about ambient temp affecting case temp but what can you say about 20c ambient temperatures?? Aircon.

    Anyway while making this guide common sense told me that if Juan or Pedro were looking up info about and trying to learn how to lap their heatsinks.. They are most likely also the kind of people who already have an idea about what you have shared and excllently explained... Some of the things you mentioned as well as stuff like how to set up proper case airflow should be under Juan's and Pedro's resume before they start lapping. I am pretty sure your explanations will really help educate the just curious readers though so lots of Kudos dude.

    Given the right circumstances... IE Good lap job, proper cleaning, proper application of thermal compound, proper mounting, proper case airflow, proper everything.. Lapping an HSF (not being specific) with an imperfect base can reduce cpu temperature. Like to emphasize the word "Temperature" <--- You're talking about heat reduction while all I have been talking about is the potential cpu temperature drop that can be gained from lapping.

    And as I have said in my earlier posts... Results will very but the average worldwide reported and expected cpu temperature drops achieved from lapping are around 3C-5C.

    Seriously bro people won't do this if it doesn't work. I wouldn't have made a pinoygeek/dsl guide version if I didn't see results. Not everybody will get positive results but lapping has worked for a lot of people.
     
  16. genemae

    genemae Member




    Sure ba kayo dyan sa mga sinasabi nyo hehehe.. Diba April Fools ngayon... hehehehe....

    May Idea ako... para siguradong Cool ang isang PC.. Ganito lang ang dapat gawin napaka dali lang po at di na pagtatalunan pa....

    Bili ka ng Freezer.. yung Malaki...
    Pasok mo yung pc sa LOOB...
    Sigurado walang paltos.. LALAMIG yun... hehehehehe
     



  17. ojpd is right, pc modding, like hsf lapping is one for the enthusiast, if you like to push your hardware more, a little bit more, then, you must be aware of what's gonna happen once you start messing up with the standard norms of pc operation. overclocking produces more heat and heat dessipation is a serious matter to consider, hsf lapping is one consideration to decrease cpu temperature if done properly. two characteristic property of a person doing pc mods is knowledge and patience. what do i get from pc modding? of course, increase performance annnnd a little kick on the ego ang a small grin on your face and then you say " kaya ko pala! "
     
  18. primus

    primus Member




    We don't experiment about the heat sink. i once worked with a company that only deals with thermal solution.

    before i engage on this thread, i would like to ask few question to all who can read this.

    1. what is the purpose of the fan? does it cool the heat sink or does it help to spread the heat across the entire area of the heat sink?

    2. if you have an ambient temp of 35c circulating around your 1000 rpm fan, what is the temp that the fan blows?

    3. What is the principle behind the liquid pipe?

    4. can you manipulate the heat? i.e. can you channel it to a different direction?

    5. which law of physics is used for thermal cooling?

    if you can answer these questions, then i will continue to add my reply here, until then... i will let you have the chance to study it carefully.
     



  19. in my opinion, thermal solution is related to where the heat is to be directed and dissipated or to convert to other form of energy. i must say thermal solution is very much related to heatsinks.
    here are some websites for further reading:
    http://en.wikipedia.org/wiki/Heat_sink
    http://www.novelconceptsinc.com

    @ primus

    a simple request, instead of asking us questions, why don't you give us answers instead, the info you can give us can really help explain the importance of thermal management.i'ts problems and solutions. thanks.
     
  20. primus

    primus Member




    @wormgear... hehehe you just posted the link where i used to work before.

    for the question #1. the answer is this. (i won't go into deep details like the formulation, laws, equation etc..etcc)

    the fan does not cool down the heat sink, what the fan does is it spreads the heat to the entire heat sink, this process is called "forced convection", in a a heat sink, the thermal is only concentrated or focused to where the heat is coming from and it will only spread naturally to a few distance from its location.

    i.e. let say you have a heat sink block of 5cm x 5cm x 5cm (h,l,wl) now imagine that the heat is coming from the center of it, the heat will spread out naturally from the center to approximately 2cm x 2cm x 2cm in radius or depending on the material conductivity, so the remaining of the heat block is not absorbing the heat, and since the applied temperature has a finite level the thermal heat will not spread further and so rendering the rest of the heat block useless, the heat can spread if there's an increase in temperature, and since the heat source such as the CPU has a threshold or finite heat dissipation, then the thermal heat will not spread any further.



    the photo above will show you how the heat is naturally conveyed to the heat sink block (courtesy of novel concepts)

    you can see that the red area is the source of high thermal heat and the green/blue area is where there's an absence of the heat.

    in able for the heat to move from the center to the remaining part of the heat block to optimize the use of it, it needs to be "conveyed" and by using an air pressure such as the fan, the heat can be dissipate/spread to the entire heat sink block, hence reducing the thermal pressure on the center (thermal source), this process is called "Forced Convection" where air is used to carry the heat to dissipate it across the heat sink, use of a liquid/fluid or other chemical to dissipate heat can also be use for forced convection (principle of liquid heat pipe) all of these are based on the Newston's law of cooling.

    the fan can cool down the heat sink, however, there's few things that needs to consider. (this will answer my #1 and #2)

    imagine that you have a sealed box with an inside ambient temperature of 40 degrees and an outside ambient temperature of 28 degrees, then you put a small fan inside the box, the intake temperature of the fan is the same as the inside ambient temperature of the box and the exhaust temperature will always be the same. Even if you use a high speed big fans you will get the same result, because the temperature that circulates inside the box is always 40 degrees. you can only reduce the internal ambient temperature by introducing a lower temperature coming from the outside.

    let say the inside and outside temp are the same, then there's no difference even if you introduce your ambient temp into the box
    40c - 40c = 0 degrees

    now, let say we will introduce a lower temp coming from the outside and feed it into the box, here's what you will get.

    40c - 28c = 12c
    12c - 40c = 28c < new inside ambient temperature.

    the fan can cool down the heat sink IF the intake temp is lower than the thermal heat source. i.e. if the heat sink block produces 50 degrees and you have an ambient temp of 28c, and you want to reduce the 50c to 30c, you must introduce an intake temp of 8 degrees lower the ambient temp.

    so the question of.. by increasing the airflow can it cool down the heat sink? the answer is no.. the increase of airflow can help to rapidly spread the heat to the entire heat block, hence optimizing the use of it.

    the principle is very basic.. low airflow slow spreading, high airflow rapid spreading,

    as for the fan cooling down the heat sink, you can only achieve to cool it down IF you introduce a lower ambient temp to neutralize the thermal source. Same principle of a common house fan, if your surrounding is hot then the fan blows a hot air too.. if you introduce a lower temp like an air conditioner the surrounding will cool off because a lower air temp neutralize the hot air.

    so even if you use a humongous fan but your ambient temp stays the same, you are just increasing the turbulence of the air, therefore increasing the dissipation speed, but the actual temp stays the same because of the ambient temp.

    those company who spend millions of dollar to design a fan for the heat sink is only to optimize the turbulence of the fan to have an equal distribution of the air pressure to the heat sink, therefore increasing the chance of spreading the heat rapidly and balanced.

    kaya nga sa mga computer casing, you must concentrate on how you can introduce a lower ambient temp to the inside ambient temp so that the HSF can benefit from it.

    as for the lapping, what it really does is, it helps to distribute the thermal heat equally across the heat sink area, hence off loading the heat pressure from the centerl point of thermal heat source and your fan can now spread the heat to the entire block, hence reducing the heat of the center.

    @ojpd,
    so yung sinasabi mong may HSF na may speed controller, all it does it to control how fast you want to spread the heat to the entire heat sink and not by cooling it.

    duon sa example mo na..
    1. If you take a heatsink that comes stock with a fan and then you remove the fan... You turn on your PC... You run a couple of torture tests while checking cpu diode temp as well as feeling it with your fingers...

    basically what happened here is this, if you remove the fan, the cpu will generate heat until it reaches the threshold and the heat will be concentrated on one place it will slowly and gradually spread to the entire heat sink, however, without the presence of ambient temp to inside of the heat sink, the heat conveyed on its own through out the entire heat block, If there is no air turbulence on your heat sink the ambient temp cannot be introduce because the cold air that was once inside the heat block is now ejected by the high thermal heat,

    but if you use a fan then you are introducing the ambient temp and injected it to the heat sink hence reducing the thermal of your heat sink because the ambient temp is now being used to neutralize the heat block, however, you cannot possibly drop the heat sink temp lower than the ambient unless an external low temp source is introduced.

    now this is not an opinion only, but a fact and adhere to the law of physics.

    hindi nating pwedeng sabihin na 30c ang ambient pero napapababa nating ng 25c ang init ng heat sink dahil sa fan lang? eh saan naman kukunin yung 5c below the ambient? unless yung ambient eh bumababa ng 5c OR nag introduce tayo ng external source na hindi galing sa ambient. i.e. coming from air conditioner or galing sa isang yelo na nasa likod ng fan. or any other means. pero kung sasabihin nating bumababa iyon dahil sa lakas ng fan, then the law of physics does not apply to the fan kasi parang sinabi nating yung fan mismo ay naka-pag create ng extrang lamig coming from nowhere, the rule is.. "what goes in is what goes out." or the principle of "a burning candle that emits 150c and you store it in a frezeer with -50c temp, the candle still burn and emits 150c"
     
                                 

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