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  • DragonBlack - Sunday, August 16, 2009 - link

    Actually, with a set up neither favoring positive nor negative, minus the disadvantages of dust being sucked in from small gaps from negative pressure, both are essentially the Same Thing if one can think slightly out of the box (casing).

    Too much exhaust in a room for e.g. with a small hole of cold intake air, it creates a hot vacuum from internal heat due to little cold air coming in. After some time, more vacuum will create a hotter casing like a vacuum flask giving you Hot Coffee.

    Too much intake on the other hand, with a small hole for hot air to escape for e.g., will slowly build up more and more pressure. No matter how much cold air coming in, if it cant escape out fast enough, the hot air will still neutralize the cold intake, going back to square one, like a hot Pressure Cooker.

    Both extremes are thus problematic. Best is to create a balance pressure like a wind tunnel effect. By standing at any one point in the wind tunnel, both ends pull and push at same pressure without disruption. Then any hot component, if placed in the centre of this tunnel, will be perfectly cooled.

    But in a typical pc setup, it is be very difficult to find out all Sweet Spots for every hot component, since all are at different locations, akin to chasing the wind. One will eventually be cooled more or less than the others.

    One method to resolve this issue, which is already done by manufacturers for their high end casings is to create 'Heat' zones, separating the casing into 2 or 3 compartments such as power supply at the bottom, hard disks on top and motherboard in the centre, then tackle it from there which is more manageable.

    Another cheaper alternative is similar to the automobile's Cold Air Intake concept with heat shielding which essentially creates thermal insulation for air filter, isolate it from the hotter engine components and re-route it to be exposed to the coldest possible incoming air.

    One will then create separate mini 'wind tunnels' i.e. air ducts with duct tapes and sealed off the whole CPU cooler, flexible air pipes etc. (a little similar to the water cooling concept, except its shielded.) then exposed it to only one intake and exhaust fans running at same pressure.

    There are, of course, other 'secret recipes' method, done by Pros, specially used for overclocking, which is constantly being researched everyday to find the Holy Grail
  • JohnWPB - Monday, December 29, 2008 - link

    Having watched this movie, i find it funny, that this does not apply to the real world.

    If we all were to get a smoke producing machine and push that smoke through our own machines, we would see the same thing... smoke going where it is pushed in, and smoke going out where there is no resistance.

    A truer test would have been like several people suggested. Do not force the air in, but let the intake fans bring the smoke into the case.

    Now for the filter remarks.

    Unless you live in a place that is very dusty, why even have filters?

    I have an Antec P182 case, that has 7 fans in it.

    1 in the lower part of that machine, that flows over 4 hard drives, and then another one behind it, that forces the air into the power supply, and then out the rear of the machine.

    1 right above the lower compartment, that flows over two more hard drives, then over the video card, and out the back.

    1 near the top of the case ( on the front panel ), that forces air straight at the memory modules, then through the fan that is on my CPU heatsink ( Thermalright Ultra eXtreme ), and straight out the back, where there is another fan that exhausts the fan.

    Lastly a fan that sits right above the CPU heatsink, that blows DOWN onto the heatsink.

    Now then, about the filtering....

    When i first built this machine, i had filters on all of the incoming fans, with the fans running roughly around 1400RPM's.

    A year ago, i took all the filters off the machine and slowed the fans down to around 1000RPM's.

    The fans get a little bit of dust on them, and to look at the interior of the machine, you do not see any dust. Why, you may ask.
    Because of the positive pressure blowing the dust out, as soon as it gets into the machine.

    Oh and by the way, the CPU in a Core Duo E6600, that is overclocked to 3.2Mhz, with both cores ideling at 31C, and going up to 43C when doing film editing.

    The moral of this story.... put as many fans into your machine as possible, take the filters off ( their useless, cause the clog up and restrict air flow ), and run your fans at a low speed so that it is nice and quiet.

    I forgot to add, that the hard drives run between 33 and 38C.
  • marc1000 - Saturday, December 27, 2008 - link

    ok, leave all the "bla-bla-bla" aside, guys. this "positive air pressure" thing really works. I tested on my own case and measured the temperature of the GPU after running 3dmark06:
    - positive pressure: 56ºC
    - negative pressure: 62ºC
    The CPU did not show any difference (the cooler is oversized), but the northbridge was noticeably cooler with positive pressure too (measured with my fingers, no BIOS reading for this)

    But my case is rather unique: it is a small mini-atx case with the PSU at the top and the motherboard on the LEFT side (yep. the CPU stays in the bottom of the case, and I open the right door to access components). The video board is a Radeon3850 with a "normal" cooler (it will not blow air out of the chassis).

    About the tested coolers setup: the default cooler for this case is a single 92mm fan that blows air OUT of the case, next to the CPU. the only other cooler on this case is the 12cm fan of the PSU. both have low-rpm (I like the silence). The case is small: 39x18x40cm, and has a lot of holes on the side panels.

    To test for positive pressure, I turned the default exaust fan to an INTAKE fan, and added another 92mm INTAKE fan on some side-openings that the right panel has. Both are placed on the very bottom of the case, just above the CPU, from the back and the right. This was enough to make more air IN than the 12cm PSU fan could take OUT. I felt a very gentle wave of air coming out from all other vents and holes on the chassis. And I was very happy with the result. So happy I will buy a 12cm low-noise fan to use in place of this spare 92mm fan, put fan-filters on both the intake fans, and live happily-ever-after.

    I know that my chassis is rare, but I think this will work perfectly for me: cool air will enter from the very bottom (right over the CPU) then take the heat to the front and up (yep, the video card splits the case in two parts), then some of the air will return and cool the GPU and immediately leave through the fan of the PSU. All this with usint silent, small and low-rpm fans. And take care of the dust is a nice bonus! Cooler and cleaner. :-)
  • JesDer - Tuesday, December 30, 2008 - link

    You testing method is completely flawed. You almost doubled the airflow in the case by adding another fan. This does not show anything about positive vs negative pressure. You also changed the way your HSF works by reversing the fan. Being shrouded this change would blow external air over the heat sink which will cause lower temps even without the added airflow. Reply
  • TimboG - Tuesday, December 30, 2008 - link

    His testing method was not completely flawed. He demonstrated that positive air pressure will affect the cooling of the GPU. I would not be afraid to guess that had he produced the same amount of negative pressure the results would have been a much higher GPU temp.

    This is only common sense. The GPU fan is trying to force air out of the case. If it is sitting within a negative pressure environment how could it be easier to push air flow against an incoming air flow?
    It is much easier for the GPU fan to push air out of the case if air is not trying to enter the case thru the GPU heatsink at the same time.

    I still protest the terrible fit of the 5-1/4 bay bezels.
  • marc1000 - Wednesday, December 31, 2008 - link

    Thanks, TimboG. my method was a little scrappy, but it was only one test and I have returned my fans to the "normal" position until I buy a good and silent 12cm fan to make a real change in my case.

    by the way, I have an Arctic Cooler Freezer 7Pro with 6 heatpipes cooling down a small Core2Duo e7200. I think that the temperature of the CPU would not change even if i turn all fans off. =D

    but my GPU is a Radeon 3850 with a "simple" hsf (it will not blow air out, just circulate the air inside the case). The added fan did not blow air directly to the GPU cooler, but to the back of the board.

    And my case is twisted to the left side too (CPU all the way down and back, motherboard on left side, PSU on top). Hard to describe, but the air will enter from the very bottom and leave on the very top, cooling the CPU, Northbridge, GPU and finally leaving through the PSU.

    My situation may be rare, but I will definetively use "positive pressure" on this chassis as soon as I can.

  • TimboG - Thursday, January 01, 2009 - link

    What I do when using a graphics card wuth the type of heat sink that your HD3850 has is to remove the slot cover that is behind the exhaust of the GPU heat sink. Or what some may say is the slot cover "below" the card mounting slot. In your case it is "above", if I'm reading you correctly.
    Then when using positive pressure in the case, the heat from the GPU will still be pushed out the rear of the case "at the GPU heat sink exhaust".

    Enjoy :)
  • marc1000 - Thursday, January 01, 2009 - link

    yes, it is "above", you are reading correctly! right now all other slot covers are "closed", but next week I will buy that new 12cm fan, some filters, and probably make this definitive change.

    We are in the middle of the new-year holidays! no shops are open today :)

    thanks for the clue, I will try it too when my pressure is positive!

  • Blain - Friday, December 26, 2008 - link

    It's a basic demonstration of air flow, at best.
    There was no "testing" done.
    "Testing" would have provided empirical temperature results.

    "Wouldn't this be a nice addition to our chassis-reviews?"
    No... Unless some real testing was done.
    Testing case air pressure as a component of CPU cooling would be interesting.
    The effects of "real" positive and negative pressures have on CPU cooling would be informative.
  • jvf - Wednesday, December 24, 2008 - link

    Been doing this for years to keep dust out of the case in nasty environments (think masonry yard, farm houses surrounded by dirt, etc. It works great. Can’t find my pics so think Mad Max with a Graingers blower grafted to the top and a cleanable K&N performance air filter attached to the blower inlet. It looks pretty nutty. I use a 12v automotive relay inside the power supply to switch it on and off with the normal case power switch. Reply
  • otherwise - Friday, December 26, 2008 - link

    This is sort of a general reply to all the filter related-comments, but this seems like a good place to dump it because it really hits the issue directly.

    I simply don't see how positive airflow inherantly solves your filtration problems.

    You have a certain volume of air that flows into your case, and a certain volume of air that flows out of your case.

    So if a positive pressure system and a negative pressure system are moving the same cfm, how is one better than the other in controlling dust? The same volume of dust particles is moving through your system!

    The only real way to argue this seems to be that a positive pressure system can have the same cooling power as a negative pressure system with less total airflow, but noone seems to be arguing this directly.
  • DominionSeraph - Sunday, January 22, 2012 - link

    The positive pressure flow will be more turbulent, keeping the dust in the air. With negative pressure, unless you have internal mixing fans, you'll likely have dead zones where air will sit and the dust in it will fall out. Reply
  • Icester - Tuesday, December 23, 2008 - link

    Why fiddle with all those fans? Just get the Chakra case (or equivalent) -- it has a nice big 250mm side-mounted fan. Then use the other "small" case fans (80, 90, 120mm) fans to exhaust over hot components. With that much cool air coming in the side, it is easy to maintain positive pressure - even when using a filter over the intake fan.

    The best filter I've found is used dryer sheets - they are cheap, disposable, conveniently available, and provide very good filtration without restricting airflow hardly at all (much better than the washable plastic mesh filters). I attach mine my affixing a bit of rough velcro to the fan grill using hot glue.
  • Ryun - Monday, December 22, 2008 - link

    As the reviews prove this, but I have a hard time believing it's merely due to the positive air pressure of the case based on this experiment alone; the experimenter is blowing the smoke directly into both fans.

    The smoke already may have sufficient velocity to blow itself through the case, regardless of whether or not the fans were on. Further, if the fans were on they may have propelled the air with a force that would have curbed the negative acceleration to allow it to move close to it's initial artificial velocity.

    On the same token, since the smoke is being blow into the case it is safe to assume the smoke machine is adding artificial positive pressure to said case that may not be attainable by the fans at all, or without a significant increase in noise generated by the fans. Both of these could have caused the dramatic effects shown in the video.

    I don't need air velocity measurements, or anything in depth to be convinced but it's clear to see Silverstone mucked the data with some bias. I would have been more impressed if Silverstone had let the smoke pass into the fans perpendicular to the fans' airflow as that could have made the result more accurate.

    ...or maybe I'm just naturally skeptical. =]
  • otherwise - Friday, December 26, 2008 - link

    I too am a bit skeptical, but instead of wall of texting people, I just wish they posted CPU/GPU/HD temps with the videos. I mean, the end result is what truly matters. Reply
  • glenster - Monday, December 22, 2008 - link

    See the thermal test results for the Silverstone Fortress FT01 at the next link:">

    It cools a CPU better than a Cooler Master HAF 932 does without the dust. Does anyone know a way to place a Noctua fan in it to cool the GPU better?
  • corsa - Monday, December 22, 2008 - link

    Look to the left.. Judging by the way the smoke is clearing soo quickly, it seems as though there is an exhaust fan drawing air from the cases rear exit.. it's out of frame of course :) Reply
  • sbuckler - Monday, December 22, 2008 - link

    Didn't look that impressive to me - mostly smoke going everywhere and no clear airflow, in particular for the cpu.

    Sure air was getting too the cpu - but the front -> back design of the heatsync it wasn't being fed properly. It was either pushing air in from above or beneath - not from the front where it needed to be pushed.
  • supremelaw - Sunday, December 21, 2008 - link

    If we compare the simple and effective designs of
    cases like the Cooler Master CM 690, it is reasonable
    to conclude all of the following:

    (1) using the natural bouyancy of warmer air
    is a good engineering principle to exploit,
    whenever possible; some vendors are implementing
    this principle e.g. by calling it the "stack effect"
    or "chimney effect";

    (2) point (1) above strongly suggests intake fans
    in the bottom panel, and exhaust fans in the top panel;
    colder air necessarily falls to the floor, and
    that is where the colder air will be found, most every time
    (unless a room heater blows heated air thru floor registers);

    (3) heat sources should be isolated in such a way that
    they intake cooler air from outside the case, and
    exhaust warmer air to the outside of the case
    without warming other components;

    (4) point (3) above therefore recommends these changes:

    (a) single high-wattage PSU should be mounted at the
    bottom rear, with an intake grill in the bottom panel,
    exhausting warmer air to the outside rear of the case;
    obviously, PSUs with higher efficiency are preferred,
    because they generate less waste heat, in general;

    (b) hot hard drives should be mounted in the upper
    5.25" drive bays, so that their warmer exhaust air
    can be exhausted immediately by fan(s) in the top panel
    again without warming other interior components;

    (c) one or more intake fans should be mounted in the
    left-side panel, to feed relatively colder air to
    video cards, CPU heatsink/fans and RAM;

    (d) hot video cards should likewise be isolated
    by taking in cooler air from those fans in the left-side panel
    and exhausting their warmer air out the rear panel --
    again without heating other interior components of the case;

    (e) a proper CPU HSF should direct its exhaust air
    directly at a 120-140mm fan mounted in the rear panel,
    or at such fan(s) mounted in the top panel;

    (f) supplementary RAM fans like Corsair's excellent design
    will help blow relatively cooler air onto the RAM DIMMs,
    as the overall air flow brings cooler air in from the
    front and bottom, and exhausts it towards the rear and top
    of the case;

    (5) supplemental fans like Antec's V-Cool should not
    be installed if they intake warmer air that is being
    exhausted by a PSU mounted at the bottom rear;
    such an arrangement violates point (3) above;
    if a PSU is mounted at the top rear, then such a
    video card cooler should work very well to take in
    cooler air from outside the rear panel and
    blow it directly onto at least one video card;

    (6) similarly, a "recycling" effect can occur
    when an exhaust fan in the upper rear panel
    emits warmer air that is, in turn, captured
    by top panel fans that blow downwards into the case;
    the latter problem is more probable if a case is
    positioned under a desk with its rear panel in
    close proximity to a wall or other solid object.

    These simple engineering principles do not cost an
    arm and a leg to implement: cf. Cooler Master's CM 690
    is an excellent example, and there are now other case
    manufacturers who are implementing these principles
    in their most recent models.

    Sincerely yours,
    /s/ Paul Andrew Mitchell, Inventor and
    Systems Development Consultant

    All Rights Reserved without Prejudice

  • mikeblas - Monday, December 22, 2008 - link

    > All Rights Reserved without Prejudice

    Wow. You're really full of yourself, aren't you?
  • Insomniac - Sunday, December 21, 2008 - link

    Wouldn't it be more real if they weren't blowing the smoke into the system? They should have the smoke blowing past the case, not into the fans. Reply
  • UltraWide - Sunday, December 21, 2008 - link

    How is this so innovative? Dell has been designing their BTX cases for the Optiplex 700-series just like this for a few years now... Reply
  • corsa - Sunday, December 21, 2008 - link

    ..that all other Silverstone cases are now under-performing & obsolete :) Reply
  • Intelman07 - Saturday, December 20, 2008 - link

    This is certainly neat. I love things like this. I've always heard negative pressure in the case is best for cooling...

    I've never actually seen a video of what happens.
  • helms - Saturday, December 20, 2008 - link

    Are the fans actually on? If not, I believe it would make more sense to see what happens to the smoke when the fans are actually on. Reply
  • whatthe - Saturday, December 20, 2008 - link

    I wonder why nobody has tried to exhaust the air from the rear top , instead of the back? I thought hot air rises. There are a lot of cases made today that install the power supply at the bottom of the case. Reply
  • mindless1 - Saturday, December 20, 2008 - link

    First, hot air doesn't necessarily rise - unless there is no other force working against it.

    Second, the point of airflow design is to make the air flow past the hot objects. Since there is no hot object pointed towards the top (Of an otherwise solid case panel in many cases), since traditional designs plan on the rear fan, it makes sense to place it there. Also, remember the goal is the longest path through the case so if air intakes through bottom front, top rear is that path and puts more pair past the mobo power regulation subcircuits.

    Having a top exhaust or intake fan can help too, in exceptional situations if a rear fan wasn't enough, but in this demonstration the main consideration would be maintaining positive pressure as it effects filtration efforts. Otherwise a couple of degrees one way or the other can be ignored since it is not a contest where that would matter, in any reasonably set up system there's far more than 2C margin for longevity or stability.

    Above all, the video wasn't a great learning lesson, it was marketing. Several ways a system can be set up and work fine, a little better or worse is dependant on objective.
  • TimboG - Friday, December 19, 2008 - link

    I just can't believe it. 10 years ago when overclocking P3 500s on BX chip-set boards many studies proved that a slight positive pressure was the best cooling solution. I for one am glad to see a case manufacturer use this as effectively as Silverstone has done with this new case.
    When the ATI 1900s came out most of the review sites were complaining about the gap between the heat sink fan shroud and the rear panel of the case. That gap was there due to how many cases were actually using negative pressure. Although most graphics cards now have closed the gap at the exhaust of the heat sink shroud to the rear of the case due to the "professional" reviewers "opinions", the cooling of these cards has suffered due to the continued trend of negative pressure within the case.
    Two thing I would have personally preferred on this case would have been a better fit between the 5 1/4 bay bezels, they've only had the standard size of the 5 1/4 to fit these bezels to for 20 years, "bout time they adjusted their stamping dies to fit it. And second, for the top inputs to be placed on a 5 1/4 movable front bezel.
  • Revolution - Friday, December 19, 2008 - link

    Little bit confused !
    But unfortunately SilverStone cases are not available in India.....:(
  • greasemonk - Friday, December 19, 2008 - link

    There is another advantage to maintaining a net positive pressure in the case with regard to dust. Since the pressure in the case is higher than outside, dust will not enter through any openings other than the intakes, which should be fitted with filters anyway. Reply
  • JesDer - Friday, December 19, 2008 - link

    As already stated, the real reason for positive pressure is for dust control. What this video shows is that you don't need an exhaust fan. The one problem I see is that without that back exhaust fan the video card exhaust is actually pulling hot air from around the CPU cooler which could actually raise the GPU temp a little. Reply
  • jmke - Friday, December 19, 2008 - link

    that this case with the front and top fans, doesn't need an additional exhaust fan. But noise wise it would be much more interesting to have NO front fan, and only one in the back; it all depends; need more movies taken with all different fan layouts to really make any sort of conclusion.

    cool test nonetheless, funny how they didn't use their own CPU cooler:)
  • Sunraycer - Friday, December 19, 2008 - link

    Oh yeah. You could increase the positive air pressue by using higher CFM fans on intake vs exhust as well, no? Reply
  • Sunraycer - Friday, December 19, 2008 - link

    Like Straightpipe, I thought the point was to have air only entering the case through the intake fan and not the misc holes. I would agree with geekfool that it would make more sense to spray around the case, though it would be much harder to see what's going on. Where I get lost is why take out an exhust fan to demonstrate positive air pressure. Taking out an exhust fan should increase the positive air pressure shouldn't it?

    I think they needed a little more explanation in this video...
  • StraightPipe - Friday, December 19, 2008 - link

    I thought the main point of Positive Air Pressure was for dust control. Basically a case has lots of seams and cracks where air can travel in and out (like the extra drive bays, I/o panels, door, etc). Ideally you should have a dust filter on every intake fan. In a case with a positive enviroment the extra pressure forces its way out of those gaps, so no dust gets in the case (without passing through the filter). In a negatie air pressure enviroment those gaps leak air (and dust) into the case from many non-point sources. That way you end up with lots of dust inside.

    It's a great idea, but it's kind of hard to get most cases to be positive. for example my case at home has lots of exhaust fans. there's a 120MM blowing hot CPU air right out the back panel, the graphics card blows out through two PCI slots, and the PSU also blows out. The only place for air to enter the case is at the bottom of the front panel. If all the drive bays are not in use I often like to add an additional 120MM on the front of the case. IT can often be put just below the oprical drive, yet still behind the front panel.

    Well my point was that they need to have the case inside a smokey room to prove that the positive pressure is keeping air from entering through cracks. Or show a bad case where the smoke pours in from the outside through unwanted gaps. They want all the air flowing into the case to go through the filters, but this video doesnt really demonstrate that.

    At least it's better than last months Video. It was just shots of the case fans running, and nothing happening.
  • mindless1 - Saturday, December 20, 2008 - link

    It's not very hard to make many cases positively pressurized, remember you are not forced to use all those exhaust fans and can opt to run the exhaust at especially low RPM.

    What is more difficult on many cases is to have the front filter panel large enough that it provides effective levels of filtration without excessive reduction in airflow.

    Why do they need to prove anything? It's your case, given that case config it is easy to choose the fans and/or fan RPM via controler to have to have it be positively pressurized. It's not about proof as-in burden on them, it's about offering a product where you still make the decisions how to use it.
  • RagingDragon - Sunday, December 21, 2008 - link

    If you want to experiment with negative vs. positive pressure, it's easy enough detach and remount a fan to switch it between intake and exhaust. Switching one or more fans should be enough to convert any case between positive and negative pressure. Reply
  • afkrotch - Tuesday, December 23, 2008 - link

    Or just make all the fans blow into the case. BAM! Positive pressure. Get air spitting out everywhere.

    This just seems like a worthless PR attempt to sell a case most ppl won't buy.
  • Spivonious - Friday, December 19, 2008 - link

    The smoke was still removed without the back fan, it's just the video cards took care of it. Reply
  • evilspoons - Friday, December 19, 2008 - link

    I don't get what the video is telling us - it almost looks better to me with the rear fan off (the smoke goes more places - i.e. the cold air goes more places - before it exits the case.

    Does this mean I should be farting around with the fans on my Antec 900, or am I ok with the 200 mm blowing upwards, the rear 120 blowing out the back, and two front 120s blowing in?
  • superunknown98 - Friday, December 19, 2008 - link

    I think the point is all the cool air came in collected heat and was completely removed. The should be no stagnat hot air remaining. This in turn should keep only the coolest air insidethe computer at all times. Reply
  • pjconoso - Friday, December 19, 2008 - link

    I'm impressed but the case costs an arm and a leg here in the Philippines, 10k+ Pesos :(

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  • ArKritz - Friday, December 19, 2008 - link

    It costs a kidney and three toes, you mean. Get with the program and make some sacrifices. :p Reply

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