Fan configuration again

WuGgaRoOWuGgaRoO Not in the shower
edited July 2006 in Hardware
With the addition of a new front bezel (i got free off directron) as well as me finding some old fans and a new zest for modding its time for me to break out the dremel.. I would like input about this configuration. I think i might want some more cfm's blowing inside, perhaps I will only have one tornado blowing out. Anyways here is a rough pic with the air flow, give me a holla at watcha think!

Comments

  • RyderRyder Kalamazoo, Mi
    edited June 2006
    I am a pretty firm believer in CFM in = CFM out.

    With the shown configuration you are at 314 out and 203 in...If you run 1 tornado you would be 195 out and 203 in which would be pretty close...so the 1 tornado config gets my vote :)
  • WuGgaRoOWuGgaRoO Not in the shower
    edited June 2006
    would you say its a better idea to have more in than out considering that there are multiple fans that wanna suck in air within the comp (gpu, cpu)
  • RyderRyder Kalamazoo, Mi
    edited June 2006
    Not in my opinion...you just need to change the air fast enough to remove the heat that is produced by those components.
    Those fan's don't "suck air in" they just blow it across the heatsink and swirl it around in the case.

    Having the high CFM fan up in the top like you have and feeding it with the fans in the front lower and the side down low like that will keep the convection going since hot air naturally rises anyway.
  • WuGgaRoOWuGgaRoO Not in the shower
    edited June 2006
    do you think if i make one of the back fans a tornado, would it interfere with the cpu fan/the psu fan..or might it just suck in whatever air the side fan is throwing in
    btw, im currently taking physics right now, so i might ask areound for a more concrete resource, but i dont feel like wasting my teachers time lol
  • edited June 2006
    Basically, if you have more CFM coming in than going out (regardless of fans blowing on components inside the PC) you will build up static pressure inside the case and the case temp will go up, leading to component temp increases. If you have more air coming out than going in, it will suck in the air it needs through all the cracks, and you'll have dust buildup at those places (basically everywhere).

    Your best bet is as Ryder says, CFM in as close to equal to CFM out as possible.
  • WuGgaRoOWuGgaRoO Not in the shower
    edited June 2006
    now how does cfm work exactly? is it that it has an effective reach of 111.9 centimeters away from the source.
  • edited June 2006
    CFM (Cubic Feet per Minute) means just that. A fan (with no load or backpressure) can move (or exchange) X CFM of air. Running a wee bit more air in is preferable to running the same amount in/out due to the PSU fan. If you pull too much vacuum on your case you can conceivibly cause the air in the PSU to stall and lead to it overheating and the fan running faster than normal.
  • RyderRyder Kalamazoo, Mi
    edited June 2006
    Cubic Feet per Minute = CFM

    It is how much air the fan moves at xxx RPM's. The rating on most fans is their CFM at full speed (which you will be at full speed if you are NOT on a fan controller)

    So you add up the fans CFM going in and what is coming out....then you try to make it equal.

    Fans going out should be near the top 1/3 of the case....in should be at the bottom 1/3 (whenenver possible)
  • WuGgaRoOWuGgaRoO Not in the shower
    edited June 2006
    hmmm i see..the only thing i'm thinking about is if the tornado on top is worth it or not..i mean it moves a lot of cfm's but will it really do enough to make a difference... i guess all i can do is check it out myself...too bad i need to dremel to find out
  • RyderRyder Kalamazoo, Mi
    edited June 2006
    A fan in the top is the most efficient at removing heat....heat rises...so it makes perfect sense.

    You may not want the tornado there...but some type of fan there is aces in my opinion.

    What in your diagram is already there....stuff you don't have to dremel?

    1 in front...2 in back and 1 in the side?

    If you haven't seen this...there is some good discussion here: http://www.bleedinedge.com/forum/showthread.php?t=3285
  • WuGgaRoOWuGgaRoO Not in the shower
    edited June 2006
    perhaps some type of 120mm fan would be more appropiate... i'd imagine i could draw more cfms..and i would have to dremel the top..the others are already there...and i figured a top fan would be a great idea due to the heat rising and such..
  • entropyentropy Yah-Der-Hey (Wisconsin)
    edited June 2006
    Also, everyone's forgetting that a case is never airtight (and rightfully so). Fans in back will pull air from the front and from all areas. For that reason, it's a good idea to figure out your airflow, but I wouldn't exactly say that you should have one in for every out. It can help, but it can also make it worse in some cases.

    Just experiment, is what I say. :)
  • LeonardoLeonardo Wake up and smell the glaciers Eagle River, Alaska
    edited June 2006
    I think your setup is really good. Hope the high number of fans doesn't create buzzing madness.

    The ideal is equillibrium - ambient atmosphereic pressure inside the case. But if there is an imbalance of 'out' and 'in', it's better to have slightly more exhaust volume. The slight negative pressure will cause air to rush in the intakes at a greater volume than otherwise effected by the intake fans alone. Considering what Madmat said - I hadn't heard of that before. Learn something every day. I don't think, however, you need to be concerned about a fan stall, as that would probably require an extreme negative pressure (vacuum).

    The dynamics that come into play when there is more intake volume than exhaust, positive pressure, is that much of the warm air in the case swirls around instead of being quickly exhausted.
  • WuGgaRoOWuGgaRoO Not in the shower
    edited June 2006
    yea.. the vaccuum/ fan stall is a concern of mine primarily because if i put a high exhaust in the back, like the tornado, right underneath the PSU, there would be severe competition for air, and obviously, the PSU would lose...and sorely i might add and as for the buzzin...ohwell... no harm no foul.. ive been building computers since the global win wbk 38 hsf was out, which was a 60mm fan which made around 65dB at a high whining pitch no less, at least with the 80mm fan, it won't be AS high..

    but the question still stands..tornado on top or a 120mm fan..cuz as of now, i havnt found a 120mm fan that has a good amount of air intake
  • RyderRyder Kalamazoo, Mi
    edited June 2006
    You will never have a fan stall.....no case is that air tight...that is also why you balance the in/out.

    Even with the Tornado at the back top under the PSU....you will not starve the PSU for air as long as all the flow is not out on every fan.

    a 120mm will be quieter and move the same amount of air as a smaller fan running faster.

    This is easy to browse and give you some ideas for models of fans...then you can search the net to find possibly better pricing, etc.

    http://www.frozencpu.com/search.html?mv_profile=searchstring&mv_sort_field=description&mv_matchlimit=33&mv_session_id=qKgZXT3I&mv_searchspec=120mm+Fan+CFM
  • WuGgaRoOWuGgaRoO Not in the shower
    edited June 2006
    yea i already looked at that site, and xoxide, and cooler guys..but nothing provides that amount of airflow..and since i just bought the fans...i kinda wanna put em in there... welp.. i guess ill tinker around figure out if the fans are worth it or not etc, etc...but i would like to modify my case somewhat this summer at least a top blowhole.. also... is it a really dumb idea to try to try to cut into plexiglass with a dremel or will i risk putting a huge crack in it while i cut
  • edited June 2006
    RyderOCZ wrote:
    You will never have a fan stall.....no case is that air tight...that is also why you balance the in/out.

    Even with the Tornado at the back top under the PSU....you will not starve the PSU for air as long as all the flow is not out on every fan.

    a 120mm will be quieter and move the same amount of air as a smaller fan running faster.

    This is easy to browse and give you some ideas for models of fans...then you can search the net to find possibly better pricing, etc.

    http://www.frozencpu.com/search.html?mv_profile=searchstring&mv_sort_field=description&mv_matchlimit=33&mv_session_id=qKgZXT3I&mv_searchspec=120mm+Fan+CFM

    Actually I've seen this happen several times over in the power supply sub-forum over at [H] Forums. There was one guy that RMA'd 3 PSUs because they were pulling in air rather than blowing it out and the fans in the PSUs were running way fast. 1 PSU he RMA'd, replaced it with another PSU (different brand) and it was still sucking air so when the first came back he put it in and still had the problem.

    All his fans weren't exhaust either, I think there was about a 40 CFM difference in intake and exhaust with the exhaust being the higher number. If the case is only going to allow a few CFM of leakage the rest has to go somewhere. Airflow like water and electricity follow the path of least resistance. If the PSU is that path that's where the air will come from.
  • jradminjradmin North Kackalaki
    edited June 2006
    Instead of using all those 90mm's, why not go with 4 120mm's? Run the front, top, and back fans at 100%. Run the side panel fan at 50%.

    The reason I say max and half is because the distance from the front of your case to the mobo is roughly 2x as far as it is for the side fan. If you put the side fan at full speed, its going to cause the air from the front fan to be sheared into generally a smaller space leaving other parts at higher temps. I use this config in my GF's intel gaming rig and the preshot rarely gets above 48C at full load. Also, less fans are going to mean less consumed wattage and less strain on the PSU.

    Now, on my own gaming rig I have 2 80mm in front, 1 120mm on the side, and 2 80mm on the back. The 120 is centered over the middle of the mobo, so the air hits the mobo and is deflected across it. 1 80mm is blowing across the HDD's and the other 80mm is blowing from the front across the 2 GPU's (7800GTX's OC'd to 510/1320 @ 58c full load on stock coolers) with 2 exhause 80mm's in the rear. This configuration keeps my towers internal temp around 34C and the CPU temp at 36C full load oc'd to 2.7 (4000+).

    I'm going to be getting a new chieftec full tower soon to start modding up again. Going to try some alternate configurations with the fans to see what else works, but the above has worked the best for me so far.
  • RyderRyder Kalamazoo, Mi
    edited June 2006
    madmat wrote:
    Actually I've seen this happen several times over in the power supply sub-forum over at [H] Forums. There was one guy that RMA'd 3 PSUs because they were pulling in air rather than blowing it out and the fans in the PSUs were running way fast. 1 PSU he RMA'd, replaced it with another PSU (different brand) and it was still sucking air so when the first came back he put it in and still had the problem.

    All his fans weren't exhaust either, I think there was about a 40 CFM difference in intake and exhaust with the exhaust being the higher number. If the case is only going to allow a few CFM of leakage the rest has to go somewhere. Airflow like water and electricity follow the path of least resistance. If the PSU is that path that's where the air will come from.
    Ok...I guess I was referring to a case fan....most PSU's try to use the least amount of fan possible to keep it quiet...so yes with a generally negative pressure in the case...you could pull air in the PSU instead exhausting it....another good reason to keep the flow balanced. Always include your PSU as part of your output calculations.
  • jradminjradmin North Kackalaki
    edited June 2006
    Especially when you have an OCZ Modstream 520 with a big'ol 120mm on the bottom of it =D
  • WuGgaRoOWuGgaRoO Not in the shower
    edited June 2006
    well it seems much like any other comp problem, trial and error works the best... ill be sure to post results etc
  • setishocksetishock marietta, Ga
    edited July 2006
    I know I'm the new guy here but I have been building on a case with airflow problems as well and here's what I found out.
    A slight negative air pressure created by the exhaust is good. But don't get carried away. The exhaust pulling slightly and I mean slightly more out than the intake pulls in makes for a good flow.
    In your drawing you have way more going out than comming in. Balance is the name of the game.
    You have 128 cfm comming in from the front.
    You have 46 cfm going out the back.
    You have 75 cfm comming in the side.
    You have 238 cfm going out the roof.
    You have 30 cfm going out the psu.
    Ok so you have 203 cfm comming but 314 cfm going out. Way out of balance. You have a 111 cfm difference between the exhaust and the intake and it favours the exhaust. If you are determined to go this route I would suggest not using the two intake fans in the front at all but instead just cut out the holes as if you were. With that much exhaust cfm's you don't need intake fans. Go total passive intake.
    Look in my profile and get my forums address and come by and scope out the stuff I've been having fits with. lol
  • airbornflghtairbornflght Houston, TX
    edited July 2006
    Hmm, if i remember correctly a couple years ago, I read this big article that someone did on the best fan configuration.

    They had multiple probes throughout the case and on the chipset,gpu, and cpu.

    They tried such combos as front only, back only, front and back, front and blowhole, rear and blowhole, front rear and blowhole, and the other combos such as a fan on the side.

    Long story short, the configuration with one front fan and one rear fan kept the computer its coolest, I am not sure why, as you'd the more air you move the cooler you could keep it. The way I figure it, is my case is *roughly* 2176 cu. in. that comes out to 1.25 cu ft. Although, there was a close second if I remember right, the one with front/back/side kept the gpu slightly cooler, but also raised the cpus temperaturea few degrees, as im sure the side fan mess up the air flow.

    So if I only have a 30 cfm fan, that means that the air in my case is being exhanged 24 times per minute. Although, Im sure we can all agree that the fans probably arent going to be putting out a full 30 cfm, as im sure the manufacture stretches the number a little bit.

    I have 3 fans on my case, 1 in the front, 1 in the back, and one on the side, I really hadnt planned the one on the side, I just had an extra red led fan, so I figured what the hell, lets do it, my computer aint that fast or super nice anyway, so lets rice it up!! lol. I just figured I'd finish the job, because my case is from like '94, and I painted it midnight blue, it has custom side and top windows cut in and plexiglass riveted to the case. I was going to put a fan up top, but there is no room.

    That is why I call my computer the ricer, because like a true ricer, I took a pos case(car) and tried to make it look better by putting flashy crap and neon on it. And like a true ricer, it has its problems, like the gaping hole in the front panel where my (ex)girlfriend *kicked* out three drivebay covers and broke them all while we were 'playing':bigggrin:



    ok, sorry about the threadjack, just had to put my $.02 in, if I could find that article I would link to it.
  • WuGgaRoOWuGgaRoO Not in the shower
    edited July 2006
    so far I added two 80mm fans on top, i found that the 120mm fan would be awkward because it would go slightly over the PSU, and instead of putting in the 80mm vantec tornados on top, i put in the "turbo cools" which are about combined 40-46 cfms heres the pic, my dremeling is not perfect, but i think it did the job


    Now, should I add a vantec stealth 120mm fan directly on top of my OCZ modstream (if i get it) it rates at 53cfm. Would that be completely useless or would it help dissapate the heat which accumulates above the PSU
  • airbornflghtairbornflght Houston, TX
    edited July 2006
    Hey, what do you use to cut the holes, if you are using a dremmel, what are you useing to cut them, a cutting wheel? if so, then is there a reason the holes are so choppy? do you trace out the line? if you do, then I would suggest slowing down, becuase I can see what looks like where you slipped, also, I have a set of hole saws that I bought, and they are awesom, just drill the pilot hole where you want it to be centered, and viola, only thing, is you have to lay masking tape down all around or else it will chip the paint.
  • WuGgaRoOWuGgaRoO Not in the shower
    edited July 2006
    well they are choppy because i am by no means an artist.. I also need to buy some more fiberglass wheels because the other cutting wheels i have are terrible... and I am probably going to purchase custom fan grills which have a larger border so you couldn't tell how bad it is lol
  • WuGgaRoOWuGgaRoO Not in the shower
    edited July 2006
    well, here we go, i think this will be my final fan configuration
    i bought 5 orange UV fans from frozencpu, they operate at 34cfms, 4 of them will be the exhaust (2 on top 2 on the side) one of them will be an intake on the side. As an outtake i also have my 600w modstream coming in (yay) and as intake i have a 119cfm tornado and a 72cfm smart fan,
    that is 221 in and 136 out (not including the modstream) so im guessing after the modstream is in, it'll be about 200 out.
    So is that too big of a difference, or should everything work out well
  • LeonardoLeonardo Wake up and smell the glaciers Eagle River, Alaska
    edited July 2006
    I think you will still have an overpressure (intake positive imbalance) problem. PSUs generally have very low volume air flow, even the units with 120mm fans.
  • WuGgaRoOWuGgaRoO Not in the shower
    edited July 2006
    thank you leo, at least i had the ability to grab a fan controller, I could probably tune down the smart fan a pitch or two.. I could also turn back to my original set up where i had a 53 cfm fan in addition to the tornado at 72 and a side fan at 30. This will give me a total of 155 in. i was orignally concerned about the OCZ fan being appx 76 cfm. Which is why i added the tornado.

    But since you are probably correct about the PSU

    jeez who would have thought that this would take this much thought
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