what do you use for case fan filters

[HotKetchup]

Would cheese cloth work? Or are there some more air-permeable things that will catch just as much dust? Maybe coffee filters?

 

[1sikbITCH]

Why don't you just buy some case fan filters?

 

[Amorphus]

I used some fiberglass window screen I got from Wal-Mart. a big huge roll for $5.

 

[mechBgon]

PCHPlayer had a good suggestion: go pick up some furnace filters and put that material behind your bezel. They're cheap, and they're made for this task. I haven't tried it yet, but it sounds logical.

 

[0roo0roo]

panty hose.

 

[0roo0roo]

that being said i find it mostly pointless. fans suck at fighting backpressure. your lowering your cooling ability just as dust would lower cooling. filters that dont block tons of air only catch the biggest dust particles. nice hepa type filters would seriously inhibit air flow. cleaning filters is a pain, not much easier then simply using a can of air and vacumn cleaner hose.

if ytou want to do it right. connect 2-3 fans in series for the intakes. stacked. this fights backpressure and will force air through the hepa filter with less loss of cfm. thats how i'd do it if i went all out on dust. then make sure its positive pressure. stacked fans don't double airflow max, they just increase ability to reach single fan max under stress. more pulling power.

 

[Mday]

what do i use for a fan filter? a fan filter of course.

 

[HiTek21]

My case has this fiberglass mesh on right behind the front cover, it doesn't capture small particles but it does capture larger particles. My new case is cleaner than my old one without a filter. I had huge dust bunnies form in a couple of weeks with only 1 case fan.

 

[Zepper]

Foam air conditioner filter material works well too. A company in Clearwater FL makes the best.
.bh.
:sun:

 

[0roo0roo]

apparently home depot sells a nice big sheet of ac foam filter for 99cents

 

[MDE]

Originally posted by: 0roo0roo
that being said i find it mostly pointless. fans suck at fighting backpressure. your lowering your cooling ability just as dust would lower cooling. filters that dont block tons of air only catch the biggest dust particles. nice hepa type filters would seriously inhibit air flow. cleaning filters is a pain, not much easier then simply using a can of air and vacumn cleaner hose. if ytou want to do it right. connect 2-3 fans in series for the intakes. stacked. this fights backpressure and will force air through the hepa filter with less loss of cfm. thats how i'd do it if i went all out on dust. then make sure its positive pressure. stacked fans don't double airflow max, they just increase ability to reach single fan max under stress. more pulling power.

Why would you use a hepa filter? You're trying to stop dust, not filter out 99.9% of allergens in the air. Just seems like extremem overkill to me, when something like a coffee filter or fabric softener sheet will do.

 

[0roo0roo]

have you actually tried coffee filters? they are lousy air filters. and as i posted above, an large open celled foam sheet of ac filter costs 99 cents at home depot. washable mesh is maybe 3 dollars. tape it to the case exterior or find some other way. those little fan filters they sell premade use the same foam, but the plastic grill looks like it obstructs flow.

and as for my hepa suggestion for insane filtering, it would filter out even the small dust particles. normal case fan filters or ac filters only filter out the biggest dust particles, you'll still have some powder like dust in your case.

 

[Bluefront]

The problem with most filter setups is surface area. An 80mm filter over an 80mm fan will be too restrictive, no matter what type of filter you use. To be really successful, you need to draw air through a filter at least three times the surface area of the fan.

Here's a setup I use successfully. All three fans in the rear of the case draw air through this filter....Nissan Xterra in-cabin filter. Good filter....this case stays clean.

 

[Icewind]

I used Antecs 1000AMG filter, but the plastic filtering was complete crap. I ripped it off and glued some light humidifier air filtering foam to clean out the dust. Works great and doesn't hinder airflow. For cleaning, I slide it out, wash it under sink, and bingo, simple as that for cleaning. As far as not trapping small dust.. well, if you dont 'like dust, I suggest you either put your computer in a vacuum or go water cooling, cause you ain't gonna avoid every single particle of dust.

 

[sodcha0s]

Bluefront,

Good idea there, but how do you keep air from entering through your CD drive(s) and cracks in your case? If you don't have all those sealed off, you'll be getting a lot of un-filtered air inside, plus filling up your drives with dust.

 

[mosco]

I just cleaned the filter on a 24CFM fan that had been going for about 3 weeks. It was covered in dust, lots of dust actually. I just installed filters on my other 2 38CFM fans.

 

[Mday]

Originally posted by: sodcha0s
Bluefront,

Good idea there, but how do you keep air from entering through your CD drive(s) and cracks in your case? If you don't have all those sealed off, you'll be getting a lot of un-filtered air inside, plus filling up your drives with dust.

i'm more worried if he has any air going through that filter at all... if you cant see through the filter, it should not be used for the computer fans. unless you have some powerful fans.

 

[0roo0roo]

well or if you have fans in series to force air through. more restrictive your filter,t he more massive oyur setup. possibly build a big wire cage or cardboard frame over the fan intake area and warp filter material over it for insane surface area.

 

[Skoodog]

hmm, I'm very interested in this "putting your computer in a vaccuum." How would this vaccuum state be obtained and with how much money are we speaking?

 

[0roo0roo]

you don't want a vacumn state, you want a slight over pressure so air leaks out of cracks. else dust sucks in through cracks where there are no filters

 

[Skoodog]

0roo, does your box run hot?

I would think so since you seem to advocate a positive pressure theory. I'm no physics genius but I seem to recall my pressure laws from high school saying that a rise in pressure rises temperature. Therefore if someone wants to cool a computer they would want a slightly negative pressure, not positive. Otherwise aren't you just blowing money on fans that are hurting your system?

I'm an ub3r-n00b so I could be totally wrong about this.

 

[Skoodog]

but back to my original question...

Has anyone ever tried o/cing cpus in a vaccuum? I'm wondering how that would affect temps and o/cing and if anyone has a link or info fof someone trying that I'd be quite interested.

 

[Match]

I just use used dryer sheets. They're essentially free since I've already bought them and used them with laundry. They don't catch everything, but they do help. When they get dirty I just replace them.

Skoodog: First off, the small pressure difference created by computer case fans would produce an undetectable change in temperature. I would hazard a guess (I could be wrong) that the fan itself would actually generate more heat than the pressure change.

Also, I think putting a computer in a vacuum would be a bad idea. You'd have to watercool everything. Not just your cpu, gpu, psu, hard drives, etc. You'd have to supply active cooling to all the little components on the motherboard, and in the psu and in pci cards that don't normally require cooling. These components (chips, voltage regulators, resistors, etc) normally cool by just radiating heat into the air; no active fan cooling is required. If the computer is in a vacuum then these components will no longer be able to dissipate their heat and active cooling of some sort will be needed.

 

[0roo0roo]

Originally posted by: Skoodog
0roo, does your box run hot?

I would think so since you seem to advocate a positive pressure theory. I'm no physics genius but I seem to recall my pressure laws from high school saying that a rise in pressure rises temperature. Therefore if someone wants to cool a computer they would want a slightly negative pressure, not positive. Otherwise aren't you just blowing money on fans that are hurting your system?

I'm an ub3r-n00b so I could be totally wrong about this.

nope, my case temps are very low. its low enough that i can get away with using a tiny 60mm~copper hcc002 cooler master heatsink with a dinky 60mm 12cfm cpu fan.

i have intake fans feeding fresh air for the video card air directly, air for the cpu and for the hd area too.

and i hate noise as much as heat. all my fans including my psu fans are hooked up to a speed controller. and most of the time, esp when its not sweltering in the summer, a ll the fans are at very low rpms. i even lower the speed on my vantec stealth fans people notice high pitch noise more then low pitch, so many reasonably large fans spinning slowly will be less annoying then a few high rpm fans.

right now i have a bit of an overkill setup(but its not really overkill when you realize many cases like the antec/chieftec come with 5 fan mounts.), 1 92mm vantec stealth bottom front, 1 92mm vantec stealth on side, 1 80mm vantec stealth on side, 1 enermax? 80mm on side, one generic blow hole led 80mm fan on top. so its 4 intakes on front and side, but those were kinda low rpm to begin with. one blow hole, and 2 fans exhausting in the antec psu. 4 control knobs, so i can control how it works out each knob controls more then one fan, so it works out. all stealths on one knob, all psu fans on another etc.

why such a mismash of fans? some are salvaged from another pc, and the design kept evolving as i added fans. it would probably be easier to just cut 2 bit 120mm holes but then again 120mm fans are expensive.

it looks like 4 in and only 2 out, but the intakes are generally run very slow, and their max speed is also lower. not to mention they are fighting through a washable furnace filter taped over em kinda weird looking, but i used masking tape on the edges to attach the sheets of furnace filter externally. it seems to work.



i'm not advocating a positive pressure case where all the fans are pushing into a more or less sealed box. that would do nothing, the fans would fight each other and total air flow would be rather pitiful. the increase in pressure would probably be equally pitiful making any temperature/pressure effect negligable. computer fans are bad at fighting against back pressure you know, its best to give em as much free air flow as is possible.

the thing to do is to have slightly more air in then out. say 3 intakes, 2 exhausts. that would work. 3 in 3 out would probably be better for total air flow since each fanw ould get closer to reaching its max air flow, but you'd probably end up sucking some dust into your case through cracks.


anyways, don't have to listen to me, listen to dan heres a bit from an old, yet still mostly relevant article. (the bit on the right side)http://www.dansdata.com/hx45fan.htm

Fans 101
The humble fan is the most important cooling component in most PCs. Without it, there'd be little to no air flow through the case. Fans can blow air into the computer, suck air out, or just move air around inside. The fan on your CPU heatsink is a perfect example of the last kind; its sole purpose is to improve the effectiveness of the heatsink by increasing the airflow over it. These internal fans do nothing to lower the temperature of the air inside the computer - in fact, they slightly raise it - but they make that air do more work.

This is only any use, though, if the air is constantly being replaced with cooler outside air. As the air flowing over a heatsink approaches the temperature of the heatsink, its cooling efficiency drops. When the temperatures are the same, no cooling happens at all - you can blow all the 50 degree Centigrade air you like over a 50 degree Centigrade heatsink and nothing's going to happen.

Standard power supply fans suck air out of the computer and create the familiar warm breeze out of the back of your PC. Sucker fans are not what you want next to your hot components, because the air they move has already passed by other warm bits of computer, and is thus already warmer. A blower fan, on the other hand, delivers air from outside the box straight to whatever it's blowing on, and thus does more cooling for a given size.

In the official ATX specification, it says that the power supply fan should blow air into the case, towards the motherboard. Since this guarantees a steady flow of pre-heated air from the nice toasty PSU, many ATX case manufacturers ignore the spec and use power supplies with the traditional blow-out fan.

Many cases also have provision for a second fan, usually (in tower configuration cases) at the bottom front of the case. If you've got a dinky little mini-tower case with no extra fan mount spot and your computer has heat problems, get a better case. Full stop. If you've got a name brand PC and you can't change the case, I feel for you.

Front-of-case fans in most situations have a pretty hard time of it. They're usually trying to suck air through a fairly narrow vent in the plastic face plate and through a more-steel-than-holes grille in the front panel. Classier cases often have a dust filter as well, which lets the air through fairly well when clean but rapidly clogs to the approximate permeability of a blanket. Add to that the fact that the plastic cages that hold front-of-case fans practically never actually seal the fan against the front panel but instead leave it a half-centimetre or so into the case, so lots of air can leak around the sides, and it's amazing that most front-of-case fans do anything at all.


Check out this cruft, from the front grille of my old case after maybe a year of service. Filter? We don' need no steenkin' filter!


You can improve the situation somewhat by sealing around your front fan with cloth-backed Gaffa (or "duct") tape, like so:



If you're feeling more adventurous but don't want to go the whole hog and fit a bigger fan, you can also cut out the metal in the front fan grille and chop a couple of extra vent holes in the plastic front panel.

If two case fans are close to each other, they should both blow or both suck. Otherwise there'll be a storm of cooling air near the fans and not enough air movement elsewhere. If two fans are located away from each other, though, one should blow and one should suck, or they'll be trying vainly to change the air pressure inside the case and will lose a lot of efficiency.

A fan will deliver its maximum airflow when it's hanging in space - the so-called "free air" situation. It will deliver its minimum airflow - zero - when it's blowing into a sealed box. In the sealed box situation, all the fan can do is move a bit of air into the box, increasing the air pressure inside, and keep it there. These two kinds of fan behaviour are governed by the two fan performance statistics - pressure and airflow.

All computer fans are roughly the same shape, so their pressure and airflow statistics are roughly proportional to their size and thickness. Different kinds of air moving apparatus have different pressure to flow ratios - a "blower", for instance, which uses an enclosed impeller to push air out of a port, has a higher pressure rating but lower airflow than a fan of equal power. A hair dryer is a good example of a blower. It's also possible to buy small 12 volt blowers which can be used in computer applications, mounted inside the case to direct a well-aimed stream of air at something that needs cooling, like a CPU.

A computer case is neither a free air nor a sealed box situation. A really well ventilated case looks to the fan pretty much like the free air situation; the more tightly buttoned up and packed with cables the case is, the more like a sealed box it behaves. The lousy mounting locations of many case fans don't really make a lot of difference to the behaviour of the box, but they reduce the effectiveness of the fan; a poorly mounted fan behaves like a less powerful one.

Arranging fans physically in parallel - next to each other, blowing in the same direction - gives twice the airflow, but only in the free air situation. The closer the thing they're blowing into is to a sealed box - the higher the "system resistance" - the smaller the parallel fan improvement becomes. Any number of identical parallel fans blowing into a sealed box will do no more than a single fan.

Arranging fans in series - stacked on top of each other, so one blows straight into the other - gives the opposite situation. There's no improvement in free-air performance, but double the pressure increase in a sealed box, and better and better performance compared to parallel fans as the system resistance gets higher and higher. Incidentally, this means that those goofy monster processor heatsinks with layered low-profile fans are a waste of money, since fans strapped onto a heatsink are very nearly in the free-air situation, and putting two layers of them there does close to nothing to the airflow.

So series fans can pump more air into a box with poor through-flow, but parallel fans will do better in a box with high through-flow. When you arrange one fan blowing into a computer and another sucking out, you're basically making a poorly sealed serial fan arrangement. The PC box leaks all over the place, so not all of the air the blowing fan puts into it exits through the sucking fan, but the arrangement is much more like serial fans than like parallel ones. This is good; it keeps the airflow up even in the card-and-cable-packed mess that is many PCs.

The exact fan arrangement to use therefore varies with the box, if you?re going for maximum efficiency. The easy way around the problem is simply to go for overkill, mount much more powerful fans than you need, and have done with it. That's certainly what I settled on. As long as the fans aren't blowing components out of the back of the computer, the problem is solved. The problems with this solution are that big fans are more expensive, computer power supplies can be overtaxed by multiple fans (a problem you can solve by using a mains powered fan), and big fans make more noise than many users will tolerate.

12 volt fans with a three-pin connector plug into the special three-pin headers on recent motherboards and can thus report their rotation speed - if the speed drops, an alarm can sound. Some fans have the three pin plug but only two wires; they'll run from a motherboard fan connection, but won't report their speed.

In the near future, we should be seeing PCs with efficient ducted cooling built in. Ducts allow the cooling air to go where it's needed, and some fanatical overclockers already use duct arrangements of varying degrees of gimcrackness to keep their sweating and terrified components cool.

 

[0roo0roo]

i forgot to mention the case interior is lined with skinned high density 1" accoustic foam on any surface i could get at it should be hot, but it isn't. its an old case, but with the mods its kept up.


here are pics http://fox302.com/index.pl?s=vg&user=oroooroo&category=Case the prefilter picture is missing one extra side intake that was added to help with the filter.


i also have normal air con form filter, but i didn't use it on this case since it seems to catch less dust. the blue filter is rather thick 1" and not that dense and allows lateral air movement, so air does gets drawn through a larger area then just the bit directly in front of the fan. its from preceisionaire. thats why i cut out such large pieces. i put normal foam in the chieftec since that one needs to be prettier