Silverstone has just released a new video about the positive air pressure they are using in the previously tested Fortress FT01 case. Silverstone's engineers used smoke to show the air circulation within the chassis which looks very impressive. We have tested this feature before with turning the large upper fan around that it exhausts the air. The temperatures were worse which shows that possitive air pressure indeed helps this case with good cooling.


Wouldn't this be a nice addition to our chassis-reviews? We will see what Santa Claus is bringing this year.


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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

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