Is there some logical reason why people don't put fans on the bottom of their case?

[DiamondFire13]

I was thinking about all of the unused space on the bottom of my case and decided that it would be a great spot to put in 2 120 mm fans. why not??? raise the case up about 1 cm off of the floor for adequite air flow. Nothing is there, it isnt part of the shell, like a side blowhole is (reducing wiring hassles), It gets the fans father away from your ear, making your case effectivly quieter, and who cares if the flow is a little restricted by the floor, although I dont really think it would be, they would still suck massive air, and even direct it in the right direction. If you have front case fans, imagine the air flowing back into your PCI cards etc first then up to the processor, with this setup, a fair ammount will just go right over them, and with a litte work, most could be re-directed over them.

Just some thoughts, give me some input if you have some cents to spare

Thanks guys,
Paul Hilgeman

 

[pbrain]

one problem is that you would get dust up the wazoo. another thing is i don't think raising your computer would be very athetically pleasing. but i think the biggest problem is that most bottom of cases would have the airflow blocked by isa/pci cards, so that you would have to put the fan towards the front, where most cases already put the front intake on the front panel. i think putting a fan on the bottom and having the air flow up is a good idea though, just as long as the case is large enough, like a large server case w/ multiple computers inside it or something.

 

[Swanny]

Well, most cases have feet on them so they are already up a little bit. I think that's all you'd need for good airflow.

And as far as dust, they make dust filters

 

[Lvis]

I recently put in two blow holes in my case. One on the bottom and one on the top. The one on the bottom blows in, and the top blows out. It has worked well, the temp in the case stays lower than the room temp, and it's only a midtower.

To make room on the bottom for the air to get in, I built a stand for the computer. It's made of oak, and there is a big rectangular hole in the center, to let the air in. It looks fine, pretty nicely done, and not having to reach as far to put in a cd/floppy etc. is nice.

It just seemed a better solution than putting a hole any other place on the case, and that space is useless anyway.

 

[MrCoyote]

Why are so many people worried about dust? It isn't electrically conductive. Besides, if you're that lazy to open the case once every 2 months to clean it... Dust is so easy to clean! Just get some Pledge or Windex and spray the whole inside of your mainboard off with it and use a rag to dust it up! Dust filters reduce air flow significantly, so I wouldn't recommend them.










P.S. don't use any type of liquid in the case to clean. I was only joking! DOH! Use a fine brush, or a can duster to blow it out.

 

[Phunktion]

It is I believe electrically capacitive.. so it would affect the components..

 

[mikef208]

So what you want to do is take all the heat that is coming from your PCI and AGP cards and blow it onto your CPU and heatsink, that doesn't sound to good to me.

 

[DDsD]

This is what im about to do to my Aopen Fulltower case, as i dont want to hack up the front bezel to increase airflow, the aopen feet give the case about an 3cm of clearance from the ground (1" for all you yanks) that to me seems perfectly adequate for a reasonable airflow, dust, well yes its an issue, but it can be combatted, when using fans this is going to happen anyway, dust just floats around in the air and stuff anyway hehe, the only downside i can see is that it, depending on the exact placement of the fans, it could rule out the use of the last slot (or two depending on how its fitted out) on your mobo, but thats not a problem, and this way it lets me blow nice cool air on my secondary video card, a nice toasty 60+ degrees Voodoo3 2k (measured on the read behind the chipzor)

i reccomeend it, its an extra place to generate airflow, cant see that as a problem...

 

[DDsD]

Oh and as for making the case quieter, im not so sure it will, as when yopu place a fan in a restiricted space (a 1cm clearance) the noice of the air itself increases as its sucked through the small gap because of the speed it must move at to normalise the pressure

or so ive found.. its not a consicerable differance, but it affects it.

 

[RmoR]

If you wanted to lower the net temp in the case, then fans located only where you suggest would be a fine idea. I don't know much about thermodynamics, but experience suggests that air blowing in the plane of the peripherals, i.e. from front to back of the box, instead of orthogonally to them would be more effective in reducing the temp of the cards. But since the less-dense hotter air rises to the top of the case, placing the fans to assist the natural process seems to make perfect sense. So maybe a combination would be best, say bottom-front, and top-back. Dust can be detrimental, though easily remedied with a filter, like another member suggested. I have a relative who experienced a nasty electrical fire caused by accummulation of dust on exposed wiring. Apparently, a high resistance circuit is set up and eventually ignites if there is sufficient quantity to get hot enough.

 

[DiamondFire13]

Hey, Thanks for all of the ideas

I was thinking about the hot PCI and AGP cards, but I dont really think it will make that much difference, when air goes in through the front, it would go very near to them anyway. I think I am going to try this with two big, slow moving fans.

Thanks guys,
Paul

 

[MattCo]

L vis - can the internal temp really get below room temp through air cooling methods?

-MC

 

[IdahoB]

Some daft stuff being said here - the temp inside the case cannot possibly be BELOW room temp - that's just not physics - me thinks you is confusing your temp sensors.

As for dust - the best thing for cleaning off dust is a compressed air canister - and there are many liquid sprays that are great for cleaning electrical componants - anything alcohol based will evaporate completely.

As for dust, it's not a huge problem, true - but too much of it

a) clogs up fans
b) acts like a brake on air flow. You know the clammy dust that clings to componants - it literally slows airflow down, the net result of which is less cooling power.

Dust filters are a bad idea - just clean the case every now and then. Any decent overclocking or hardware enthusiast opens their case so often they don't have a chance to get dusty - just keep that can of air in the drawer and give it a blow

 

[Jex]

Case/computer temps CAN NOT go lower than the ambient temp in the room. It's impossible unless you have some cooling source, like cooler air from outside or some water evaporation cooler or something.

 

[Jeff7]

I'll second what Jex said; fans just move air, they don't actually reduce its temperature.

Dust is also bad in that if it sticks to a heatsink, it limits the amount of air that can directly contact the heatsink.
Why are dust filters a bad thing though?

 

[Lvis]

Sorry Guys, don't get all excited, my post was poorly written.

It is cooler, in that the room temp is taken from the thermastat that is about six feet off the floor. Warm air rises, so it's warmer where the thermometer is. The air temps where the case is are cooler, it's about five inches from the floor.

The point I was trying to make is that the system works pretty well, and the temp in the case is at least no warmer than room temp. (at least it hasn't yet, in the three weeks or so I've had it set up)

Again, sorry for my poor choice of words.

 

[gimps]

I believe it is possible to be below ambient room temp. The floor in my room is not covered, still bare concrete. If I put a fan on the bottom, it would be blowing cooler air in, due to the coldness of the concrete.
Then again, I could be wrong. This is just what I think.

 

[alpineranger]

The worst thing about dust is that it carries a (static) charge. The charge often transfers to whatever it lands on. If you get enough charge in your case through dust particles, you can ruin a lot of ESD sensitive components. Trust me, it is possible, and I've had firsthand experience with this problem.

 

[Wik]

Don't be so worried about the dust. OMG have you ever opened an old Compaq in some office that has not been touched in years and is still running? Now that is dust!

 

[Def]

Aluminum mesh filters barely decrease airflow and trap a large percentage of the dust going through the case.

Those plastic/foam filters suck though, way too restrictive.

I think all the people speaking out against filters have never used them and don't know what they're talking about. I recommend the mesh filters to anyone that is adding more fans to their case. You still have to clean your components, but the dust accumulation is not near as bad. Plus in places like dorm rooms and such, your HSF can get such a thick layer of dust that in a week you hit 2-3C higher temps under full load due to reduced heat transfer.

 

[WarCon]

I am apologizing in advance for this......, but I just have to bore you all with a dust horror story.

I went to a friends house who by the way has 4 APC German Shepards(important to story) who are pretty much allowed the run of the house and the yard (which is mostly mud when wet). Anyway this system was only 6 months to a year old and I was coming over to install their new scanner for them. Was SCSI so I had to open the system.

WOOOOOOOOOOWWWWWWWWW is the only word I have for what I saw. I guess that the intake fan on computers works real well to vacuum the air. These dogs go outside roll in the mud then inside to romp and play and shake and scratch......well you get the point. What I saw would of shocked you and for the proponents of the dust kills perspective I was amazed. The motherboard (desktop model so its laying horizontal) was not recognizable as an electronic component. It looked like bare earth. Only where I bumped the cables as I pulled the case off was anything but dust(dirt) visible, but the thing was running just fine.......:Q

Anyway after taking it into the garage and using the compressor (yes I know that fast moving air can damage components and build static, but didn't have choice) it looked just fine.

 

[Wik]

LOL