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(NVIDIA) Fan-Based-Heatsink Designs are probably wrong. (suck, don't blow ! heatfins direction)

Discussion in 'Nvidia' started by Skybuck Flying, Aug 18, 2012.

  1. Hello,

    I am starting to believe that NVIDIA's Fan-Based-Heatsink Designs like the
    recent GTX 690 are totally wrong !

    And here is why:

    The heatsink fins are placed in the same direction as the airflow. This will
    cause dust to easily get stuck between the heatsink fins and especially in
    front of it.

    THIS IS WRONG. This will cause the heatsink to get full of tiny little hair
    pieces and dust particles.


    Place the heatsink fins 90 degrees turned so that the overflow must go OVER
    the heatsink fins and not in between.

    So here is a picture to show the wrong situation and the better situation:

    top view of card when place on table:



    --------------------- <----- airflow | FAN
    <--airflow--- -----------------------


    | | | | | |
    | | | | +------+ | | |
    | | | | <---- airflow | fan | <--- airflow | | |
    | | | | +------+ | | |
    | | | | | | |

    This better design should hopefully and be designed in such a way... that
    air/heat GETS sucked out of the heatfins by blowing air OVER IT and not in
    between... to reduce the chance of stuff getting stuck in it !

    So there should be some room OVER the heatfins to be able to blow air
    through it.

    Skybuck Flying, Aug 18, 2012
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  2. Additional:

    Since my horror experience with the 7900 gtx cards I am afraid to buy
    graphics cards with the nvidia heatfins direction.

    I am afraid that the graphics cards heatsink fins will get full of dust and
    stop to function !

    My newest passively cooled graphics card is actually also an nvidia/asus
    design. Where the heatfins are in the direction against the airflow.

    So far there is probably no dust in side of it... or very little... which
    seems to be much better.

    If nvidia wants my bussiness back they will have to design cards which can
    operate for the long term, without requiring any cleaning what so ever.

    I am not going to open up my PC and risk damage during cleaning operations.

    NO CLEANING operations should be necessary.

    THEREFORE nvidia must design graphics cards which will operate for a long
    time... 5 to 10 years of blowing/sucking air.

    Perhaps the heatfin direction that I proposed is less optimal in the short
    term... but will probably be optimal in the long term.

    Therefore my advise to nvidia which they hopefully already have:


    2. TEST the graphics card heatsink design for as long as possible... and
    test the situation with dust build up.

    3. Build the graphics cards which has the least problems with dust build up.

    Otherwise you can go to hell... I do not ever want to face overheating
    problems because of gpu overheat/heatsink full problems ! ;) :)

    Skybuck Flying, Aug 18, 2012
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  3. One last explanantion/addition for any potential dumbos out there to explain
    the "suck, don't blow" part of the title.

    The idea is to:

    BLOW air OVER heat fins.

    Hopefully this will create some kind of suckage effect over the heatfins and
    suck heat from between the heat fins and blow it away.

    This might also have a beneficial effect of sucking any dust/hair particles
    out of it and blowing it out.

    That's the idea at least... which would be very nice.

    I am not sure if it will work like that in practice... since there is no
    opening on the other side of the heat fin to suck from....

    So maybe some kind of vacuum would result from it...

    If that is a good or bad thing remains to be seen/tested.

    Very maybe openings could create on the other side... but that would
    probably start to suck dust between the fins which would be bad.

    So experimenting with this idea is required to see what works best long

    My only worry would be that the opposite might happen, maybe dust will start
    to fall down between the heatfins....

    What will happen in reality I don't know...


    Perhaps someday... a dust particle simulator might show what happens ;) :)

    Skybuck :)
    Skybuck Flying, Aug 18, 2012
  4. Skybuck Flying

    MrTallyman Guest

    You are an idiot.

    They suck so that YOU still have direct access to clean the tines of
    the heat sink. If they blew, the heat sink would get plugged up in a
    place under the fan, and you would have to remove the fan to clean it.

    Now shut up and go away and stop making posts which you are then the
    only idiot who responds to it the first 5 times!

    Grow up, child! You are immature AND stupid. Get over it. Leave US
    out of it.

    You are a very particular type of Usenet idiot, and you are blind to
    MrTallyman, Aug 18, 2012
  5. Skybuck Flying

    John Larkin Guest

    And reduce the chance of getting heat out of it.

    Even better, aim the fan at something else a foot or two away.

    You are of course assuming that you know more about cooling a CPU than
    all the people who currently make a living cooling CPUs, including the
    MEs in charge of thermal design at Nvidia.

    I have this theory that the fins of a heat sink should reduce a fan's
    free-flow rate by 50% for optimum heat transfer.


    John Larkin Highland Technology Inc
    www.highlandtechnology.com jlarkin at highlandtechnology dot com

    Precision electronic instrumentation
    Picosecond-resolution Digital Delay and Pulse generators
    Custom timing and laser controllers
    Photonics and fiberoptic TTL data links
    VME analog, thermocouple, LVDT, synchro, tachometer
    Multichannel arbitrary waveform generators
    John Larkin, Aug 18, 2012
  6. Skybuck Flying

    Flasherly Guest

    Unless chambered to stop air flowing in for an arbitrary 10-25%
    reduction of motor shaft speed, equal to chambering outflow, or both
    chambered, as opposed to an effective vacuum, which might further
    indicate where motor design is outside operational efficiency,
    irrelevant of equipment MTBF, and provided there's salience to some
    residual mean temperature for cooling to be a factor in coincident
    significance to ascribe at the proposed structural end as an operative
    upon RPM.
    Flasherly, Aug 19, 2012
  7. Umm, you would not perchance be employed in a government position (spin
    doctor) ??
    Rheilly Phoull, Aug 19, 2012
  8. Skybuck Flying

    Robert Macy Guest

    optimum heat transfer? not sure what the criteria would be, but think
    instead about the air's thermal mass, thermal resistance form metal to
    bulk air. and you see you're left with characteristics of the heat
    sink, not the characteristics of the fan.

    As a mind argument enfisionone hell of a powerful fan. Now block that
    to half flow, what do you have? versus an 'underpowered' fan that is
    blocked to half flow. .
    Robert Macy, Aug 19, 2012
  9. Skybuck Flying

    DK Guest

    When a video driver installation takes 200 MB on a hard drive
    and is still full of bugs, there is every reason to question designers'

    DK, Aug 19, 2012
  10. Skybuck Flying

    Quadibloc Guest

    The reason the heatsink _has_ fins is to maximize the contact area
    between the heatsink and the air. So you also want to maximize the
    velocity of the air in proximity to every part of the heatsink, so
    that there is a larger temperature difference over as much of that
    large contact area as possible.

    One puts a dust filter in front of the intake vent to keep dust out of
    the fins, although dust generally does not collect where there is a
    violent wind.

    What you really want to do, though, is use a working fluid other than
    air which can carry more heat away. Of course, the Montreal Protocol
    because of the ozone layer makes that more complicated; the other
    alternative requires careful precautions because it becomes
    electrically conductive very easily by dissolving material.

    But a third alternative to setting up a refrigeration system and using
    chilled water would be using chilled mineral oil. Of course, there,
    flammability is a problem, although the fractions typically used for
    such purposes aren't too bad...

    John Savard
    Quadibloc, Aug 19, 2012
  11. Skybuck Flying

    SC Tom Guest

    That's a different group of engineers. I doubt seriously if the design
    engineers are also the software engineers, although there is probably *some*
    collaboration between the two groups.
    The design engineers I worked with had a motto: "If it ain't broke, redesign
    it!" No such thing as leaving well enough alone :)
    SC Tom, Aug 19, 2012
  12. Come on. That's software vs. hardware. The engineers may design and
    build superb hardware, but if the software isn't up to scratch, it's
    wasted effort. Look at ATi/AMD cards, for instance. Good hardware,
    lousy drivers.
    Mike Tomlinson, Aug 19, 2012
  13. Skybuck Flying

    Flasherly Guest

    If I had my druthers, I'd as rather gainfully, that is contractually
    and under government auspices, to be on your tax dollar, sic, whereby
    to impose mandatory interpolation of required observances, forthwith
    said forthrightly, such that as an agreeable conscientious citizen,
    I'm sure you are, there could be no other possible meaning given you
    to mistake my greater schemes.
    Flasherly, Aug 19, 2012
  14. Skybuck Flying

    John Larkin Guest



    John Larkin Highland Technology Inc
    www.highlandtechnology.com jlarkin at highlandtechnology dot com

    Precision electronic instrumentation
    Picosecond-resolution Digital Delay and Pulse generators
    Custom timing and laser controllers
    Photonics and fiberoptic TTL data links
    VME analog, thermocouple, LVDT, synchro, tachometer
    Multichannel arbitrary waveform generators
    John Larkin, Aug 19, 2012
  15. Skybuck Flying

    John Larkin Guest

    Minimum theta would do.

    but think
    If the heat sink doesn't reduce air flow at all, the air is going
    around the fins, not through them (as Skybuck suggests) and the air
    does no good. And if you block all the air flow, it does no good. So
    the amount of airflow restriction that results in the lowest theta
    must be somewhere between those two extremes. Dead center is a pretty
    good guess.


    John Larkin Highland Technology Inc
    www.highlandtechnology.com jlarkin at highlandtechnology dot com

    Precision electronic instrumentation
    Picosecond-resolution Digital Delay and Pulse generators
    Custom timing and laser controllers
    Photonics and fiberoptic TTL data links
    VME analog, thermocouple, LVDT, synchro, tachometer
    Multichannel arbitrary waveform generators
    John Larkin, Aug 19, 2012
  16. Skybuck Flying

    DK Guest

    I realize that. Just couldn't resist. Plus, I think it points to some
    fundamental management/business philosophy problems that are
    very likely to influence all layers in the company, harware included.

    DK, Aug 19, 2012
  17. If the input and output temperatures were the same, that might be
    true. It might also be true if you consider the reduction in free
    flow rate caused by the back pressure due to the head sink obstructing
    the air flow.

    However, air expands when heated, causing an increase in air flow at
    the exhaust end. That's why the exhaust port for a heat removal
    system is larger than the intake. My guess(tm) is that the increased
    exhaust air flow caused by heating is much larger than the reduction
    in intake air flow caused by the fins getting in the way.

    On the original assertion, that it's better to suck than to blow,
    methinks that's wrong. You can demonstrate this with a dirty
    computer. Take a vacuum cleaner and try to remove the dust by
    sucking. Most of it will still be in the machine when you're done.
    Now, put the hose on the same vacuum cleaner exhaust and blow the dust
    out of the machine. Notice that remaining dust is effectively blown
    all over the room.

    It's dispersion versus concentration. When sucking, one pulls air
    from the sides and from all around the heat sink, including air that
    does not need cooling. This makes the fan work harder moving excess
    air, leaving less air flow for between the heatsink fins. Turn the
    fan around and blow air at the heat sink, and the entire air flow is
    involved in cooling the fins.

    Similarly, you can demonstrate the effect by comparing the CPU
    temperatures with the fan in the normal position (blowing air down
    towards the heat sink), versus flipping the fan over and sucking air
    out. I did this with a Pentium 4 dual core. I forgot the measured
    temperatures, but the difference was substantial.
    Jeff Liebermann, Aug 19, 2012
  18. What you want is immersion cooling:
    Build a leak proof package, insert computer, fill with fluorinert,
    mineral oil, anti-freeze, distilled water, or whatever and it will
    redistribute the heat to a much larger mass and surface area.
    Jeff Liebermann, Aug 19, 2012
  19. Given the same mass/sec flow of air over the fins of a heatsink,
    the best heat transfer is by blowing due to the greater turbulence -
    which disturbs the boundary layer of air that lies in contact with
    the fins and puts more flowing air in direct contact with the surface
    of the fins. In the case where the fins rise up away from the source
    of the heat, it's best to blow downward from the ends of the fins
    toward the source of the heat. IOW, the air should move in a
    direction opposite to the heat flow.

    This principle is not only used in heat transfer systems, but also in
    biological systems in oxygen transfer through membranes - as in
    fish gills where the blood moves across the gill membrane in a
    direction opposite to the flow of water. The basis of this principle
    lies in the finite heat (or gas) capacity of a fluid and that greatest
    heat (or gas) flow occurs as a linear function of the difference of
    temperature (or gas concentration) between 2 bodies. Apply a little
    calculus, and the principle of opposing flows results. This design
    principle was recently seen when I opened up the case of a friend's
    PC to clean it out: The cooling fins for the CPU rose up from the CPU,
    and the cooling fan blew air down along the fins toward the CPU.
    Obviously, the designer had paid attention during college freshman

    Timothy Daniels, Aug 19, 2012
  20. Skybuck Flying

    Tim Williams Guest

    Oddly, my new, stock heatsink is designed with fins arranged
    not-quite-radial, in an X pattern around the center. It looks like
    extrusion oriented axially (axis normal to the processor face), rather
    than transverse. The fan blows air over the center and fins.

    At 100% CPU I get 42C tops, so it seems to be doing its job. Nothing
    special, a dual core 3.2GHz Athalon II. It's also entirely possible AMD
    (or whoever they contracted to make them) doesn't know their physics.

    Note that heat transfer by volume isn't usually the goal, so much as
    minimum temperature is. In a counterflow setup, the hottest part of the
    heatsink is cooled by the hottest air. If you flip it around, the hottest
    part of the heatsink gets cooled by the coolest air, achieving the highest
    heat flux for a given surface area and temperature difference -- more
    power density, at some expense to mass flow and pumping loss. You might
    avoid this, for example, if you had to use pure nitrogen (or helium, for
    that matter) for some process, minimizing the gas flow to keep operating
    cost down.

    Tim Williams, Aug 19, 2012
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