* Basic Guide to Improving Case Airflow*

Discussion in 'Overclocking & Cooling' started by doyll, Oct 24, 2019.

  1. doyll

    doyll Kyle's Thermocouple is HOT

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    How airflow works
    Airflow is simply displacement; for air to come into case, air must be leaving case .. or .. for air to leave the case, air must be coming into case.
    Think of the air around us as water and we are divers in it and a sunken van is a computer case.
    • We can't move more water into the van (case) through an open window (vent) unless we have another open window (vent) somewhere else in the van (case) moving the same amount of water (air) out through a window on other side of van (case).
    • We can't take any water out of van unless we have the same amount of water coming in at the same time.
    • This means we have to have as many open windows flowing water into van as we have open windows flowing water out.
    • This is exactly how airflow works. Intake fan pushing / flowing air into case is pushing / flowing the same amount of air out of case.
    • Adding an exhaust fan can help case airflow, same as adding a back fan on some coolers.
    • But with good case intake fans we don't need exhaust fans, same as good cooler / radiator fans don't need pull fans. [​IMG]
    • This is why I used to always change stock intake fans. Now some cases are finally coming with intake fans that have high enough pressure ratings to not need 'helper' (exhaust) fans. [​IMG]

    Setting up a case for optimum cooling

    Setting up the case for optimum cooling is often the hardest and most time consuming part of a build... And the most neglected by most builders.
    • There is much more to cooling than good cases and good CPU / GPU coolers. Add the fact that many GPU's make more heat than CPU means getting that heat out of the case and keeping a cool airflow to components can be a challenge.
    • Cases, especially those with filters, usually benefit from fans with higher static pressure ratings than stock fans... "cooler" fans instead of "case" fans.
      Intakes typically have more restricted than exhaust because of air filters, more restrictive grills, HDD cages, etc.
    • I prefer mostly just good pressure rated intake fans and rarely use exhaust fans anymore .. but instead use high enough pressure rated intake fans with exhaust vents being the only other openings in case. This allows intake fans to push air though the case and out. And don't confuse number of fans with amount of airflow... don't confuse airflow with airblow
    • airflow is flowing cool air from intake to component and then flowing component's hot air on out of case without that heated air mixing with the cool air and warming the air going into component.
    • airblow is lots of fans blowing air around, both cool and hot air from components allowing them to mix and raise the air temp going into components .. because basically every degree warmer the air into component cooler results in component being a degree hotterl.
    • Putting in good intake fans in case and maybe exhaust is only the first step. These fans only move air in and out of case.
    • This does not mean heated air is not mixing with cool air.
    • Nor does it mean cool air is going to where it is needed.
    • Getting the air to flow inside of case properly is even more important. We still need to manage where the air flows inside the case. We can do this several ways; deflectors, more intake fans.. & maybe exhaust fans, removing vent grills, removing HDD cage/s, using fans with higher pressure/airflow, building ducts to or from CPU/GPU cooler, etc.
    • Using a remote temperature sensor to monitor what air temps are is the key to finding out where the cool air is flowing and knowing heated air is not mixing into it. By monitoring this we can than make changes to get airflow the way we want it.
    • Keep in mind your case needs to flow more air than components do. It isn't so much how many fans but how well they flow air through the case. If component fans move more air than case fans move through case components are using their own heated exhaust to make up the difference and case heats up. Good rule of thumb is 25-50% more case cfm than component cfm but well tuned airflow can be almost equal equal.
    • Traditional tower cooler exhausting toward back of case must have rear / rear & top back case venting airflow area equal to intake airflow area .. they need to be able to flow more air than components are using .. more cfm than cooler fans have.
    • A duct from back of cooler to back of case (like Thermalright HR-22 uses) is also an option that works very well.
    Example of Cool & Quiet System
    • Define R2 system has three TY-140 74cfm intake fans. (no exhaust fans) in case while CPU has TY-143 130cfm fan and GPU has two TY-100 44cfm fans
    • Case = 222cfm
    • Components = 218cfm
    • Air temp inside of case going into coolers is never more than 3c above room.
    • 2 front TY-140 1300rpm intake fans match airflow demands of CPU cooler TY-143 2500rpm fans, both PWM controlled by CPU fan header
    • Bottom TY-140 intake fan supplies airflow demands of & GPU TY-100 fans and are PWM controlled by GPU

    It is amazing how much cooler a system runs (and quieter) once the case airflow is setup to keep heated exhaust from contaminating cool intake air. Once we start doing these things, the concept seems like a no-brainer, yet most users seem to think more fans and/or powerful fans are needed to get better cooling. The reality is it's not so much the power and amount of air the fans move. but the currents / pathways the air flows in on it's way through the case that is important. Fan power/airflow only needs to be a little more than the amount the components are using at any given time. Using too many, fan and having too much airflow airblow can be as detrimental to case's flow pattern as not using fans with enough flow .. and if the flow isn't tuned to keep cool and heated air separate the system is not going run as cool as it can.


    How to monitor air temperature different places inside of case:
    • A cheap indoor/outdoor thermometer with a piece of insulated wire and a plastic clothspin works great.
    • Made up with floral wire and tape. We don't want anything to short out with metal. [​IMG]
      LL.jpg


     
  2. NightReaver

    NightReaver n00b

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    I fully agree with this. I have my gpu/cpu watercooled with 8 intake fans and after awhile thought why do I need other fans? It seemed that there was more than enough airflow to push its way out of the case. Sure enough I took all the extra fans out and closed her up and what do you know, VRM/mobo temps didn't increase at all. Yet just about every single guide you find online is all about "Gotta have an equal number of exhaust and intake", oh, and also "Don't you dare put intake fans on top!".

    So much misleading info constantly regurgitated without anybody actually testing it. People need to do more case by case testing for optimal fan layout, instead of using catchall "rules" that don't really apply.
     
  3. doyll

    doyll Kyle's Thermocouple is HOT

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    I've found the smoother the airflow / less turns the better, so I generally don't use top vents. But there are some cases that don't have bottom intake and/or emough front intakes to supply all the air used by component fans so an intake in top near front can help. Sometimes I use file folder as material to make a defelctor to turn the air coming in top back toward CPU cooler.

    Another problem is how restrictive not just filters, but grills and even pressed metal mesh or wire ring grills are quite restrictive. See next post.
     
  4. doyll

    doyll Kyle's Thermocouple is HOT

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    Grill & Filter Effect on Airflow & Noise level
    Click on to view


    [​IMG]

    http://www.silverstonetek.com/techtalk_cont.php?area=en&tid=wh_chessis
    Scroll down to see how air flows through round wire grill versus punched metal grill.
    Click on to view
    [​IMG]
    https://www.pugetsystems.com/labs/articles/Effects-of-Grill-Patterns-on-Fan-Performance-Noise-107/

    Here is a drawing of basic grill mesh designs showing what their open area / airflow area is. Notice hexagonal / honeycomb patterns have much more open area for air to flow through.
    LL.png
     
    Last edited: Oct 24, 2019
  5. PhaseNoise

    PhaseNoise [H]ard|Gawd

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    This is awesome, thanks for sharing your expertise doyll!
     
  6. M76

    M76 [H]ardForum Junkie

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    Good guide for newbies. The only thing I'd argue with is that if you need ducts or deflectors you're doing something wrong.

    And don't diss negative air pressure builds, they can be done right. And necessary in some situations.
     
  7. VanGoghComplex

    VanGoghComplex [H]ard|Gawd

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    Interesting read! With all that in mind, how would you cool this case?

    https://www.raijintek.com/en/products_detail.php?ProductID=54

    My gut was to intake on top and exhaust on back, but that doesn't make sense, does it? If I intake on both and just let the PSU fan be my exhaust, I'm getting cool air directly over GPU and CPU.
     
  8. doyll

    doyll Kyle's Thermocouple is HOT

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    All depends on the case. As I said, some cases do not have enough front and/or bottom vents to supply the amount of air some coolers (CPU & GPU) use. Example is CPU cooler with 1500rpm 140mm fan and GPU with 3x 80/90mm fans is 154 + 191 = 345 sq cm of airflow area into coolers. That is more than 3x 120mm or 2x 140mm fans have. As case intakes usually have fancy grills that are even more restrictive than rear venting plus a filter adding even more restriction to airflow means even with equal airflow area intakes need to have at least as much area (more is better) and run about 30% faster than similar size cooler fans to supply a little more cool air than component coolers are using. So we end up needing 4x 120mm or 3x 140mm intake fans in the front and maybe bottom of case to supply the cool air demands of components. If case only supports 2x front 140mm fans and has no bottom intake vent than we need more intake airflow, so a top vent near front will help, but it's blowing air down, not back, so a curved deflector / duct to turn it's airflow toward CPU cooler/ back of case helps keep airflow moving smoothing back to CPU / out back venting.

    I dismiss negative air pressure builds because they let dust in every tiny hole, fitting, socket, etc. in the case. Please give us an example of why a negative pressure would be necessary. Only one I can think of is owner has a case not designed to flow air like it should, in which case they should get a better case.

    But we need to keep in mind the amount of pressure differential computer fans make is very little.
    The difference in pressure between sea levele at 20c and 10 feet above sea level is only 36 Pa which is 3.671 mm H2O. So the difference between sea level and 5 feet above sea level is 1.84mm H2O. NF-A15 cooler fan creates 2.478mm H2O @ 1623rpm but only 0.57mm H2O @ 797rpm. TY-143 makes 4.19mm H2O @ 2145rpm but only 1.02mm H2O @ 1055rpm. PH-F140MP makes 2.286mm H2O @ 1416rpm but only 0.51mm H2O @ 683rpm.

    Typically my builds have case fans running in 500-1300rpm range. 1000rpm with stress load on CPU or GPU, air into cooler is 3c above room ambient. 1300rpm with both running stress load, air into coolers is 3c above room ambient. That is in cases supporting 3x or 4x 140mm intake fans front and bottom with case raised on taller feet or open center caster base.
     
    Last edited: Oct 25, 2019
  9. Brian_B

    Brian_B 2[H]4U

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    Air flow on the CPU HSF isn't the same as air flow through the case.

    A HSF isn't typically directly pulling from or drafting out of a case vent. It's circulating air inside the case. The HSF isn't creating a differential pressure through the case or driving air in or out - and that's the critical difference. And just because you have a large HSF doesn't necessarily mean you need a ton of case ventilation - energy is the ultimate variable. If your dumping a lot of energy into the case, you need to remove that energy. Having 345 sq cm of fans cooling 15W of total load isn't going to require a lot of case ventilation, no matter how fast you have those internal fans spinning.

    Also, you mention the size of the fan with relation to area of air flow. That has almost nothing to do with anything. Sure, big fans can move more air than smaller fans, but not necessarily - you have to look at fan speed and blade design - a small fan running at a really high rpm can move more air than a larger fan... if your just looking at size and saying you need to match up surface area, that isn't correct at all.

    And I'm lost on what elevation change has to do with the static pressure of your fan. Sure, if your designing a HVAC system for a skyscraper it makes a big deal. Inside a case... not really so much. Maybe I'm missing some critical variable here, but air just isn't that dense and your somehow using the density of water in your air flow calculation.

    HSFs dump heat from the CPU to inside a case. Same with most non-blower GPUs - from the GPU to inside the case. It's the job of your case to remove that heat from the case. Your OP is spot on, but this reply just doesn't seem to make any sense.
     
  10. doyll

    doyll Kyle's Thermocouple is HOT

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    Seems you are nit-picking and trying to cause problems with some of your post.
    The evevation change is an attempt to give readers an idea of just how low computer fan presure differential is .. less than the difference between sea level and 10 feet above sea level is not enough for use to notice any change in pressure .. that is now little 3.671 mm H2O is .. and that is much higher pressure rating than any fan I own makes.
    Look at English fan specifications and you will find the static pressure rating of fan is in mm H2O. Static pressure rating is the maximum amount of pressure the fan can make pushing air into a sealed container .. not something we use our fans for, but gives us an idea of how well they can overcome airflow resistance.

    Airflow is airflow. Case fans really don't direct very well, but the to tend to push a cone shaped flow of about 90 degrees.

    The key to good case airflow is not having air 'circulating insdie of case' but flowing from intake to exhaust while passing CPU and GPU coolers. This is why front to back is usually best .. because air enters front (maybe one bottom), flow back over GPU and CPU, then out back vents / open PCIe slots.

    Yes, the cooler fan is created pressure differential. Pressure differential is how air is moved. Higher pressure air moves into lower pressure areas thus threating movement.

    If anything we need more case intake area and fans than cooler fans because case intake is many times more restrictive thus requires much more powerful fans or more total number of fans to pull air in through restrictive grill and filter than is needed to flow air though cooler.

    No energy is required to remove air from case. Only simple pressure differntial and vent area. All air entering case must leave case for more air to enter. It's simple displacement.

    The key to setting up case airflow is not '345 sq cm of fans cooling 15W of total load' but having enough potential airflow to cool maximum load of like 150W on CPU and same on GPU. We need case intakes to be able to flow a more than cooler will be at 100% load with fan at or below full speed. Then set their fans speeds to flow air as needed to keep both components at reasonable temps.

    Of course fan speed, blade design, even restriction of airflow, etc all enter into case airflow setup. We generally have/use 80/90mm fans on GPU, 120/140mm fan/s on CPU and 120/140mm case fans. 2x 140mm fans will flow about the same as 3x 120mm of similar design and speed. Most/many of us never run 120/140mm fans above 1200rpm because we want near silent systems., but most fan max speed is 1300-1600rpm so we set fan speed curves to keep temps same and fans quiet.

    |You are simply not understanding my post. Maybe my fault, maybe yours. First post in general guide. Last post was more detail / technical to layman explaination.
     
  11. Brian_B

    Brian_B 2[H]4U

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    Yeah...
     
  12. doyll

    doyll Kyle's Thermocouple is HOT

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    I should have said, no exhaust fan is need, so no addtional energy is needed. If we get into pure science then yes, there is some energy expended in overcoming friction of grill, etc. Overall temps of components are maybe 2c warmer without exhaust fans, but an additional 50-75rpm easily bring temps down 2-3c and as fans never run full speed it's not an issue. Some of my build I cut rear vent grills out and use simple wire fan guards. but they are getting harder and harder to find. I've even gone as far as cutting half the rings out of them. This kind of wire grill creates much less airflow resistance. But there is a point of no return and we have to let common sense prevail. ;)

    Gdstime-140mm-Metal-Fan-Guard-Protective-Grill-for-PC-Ventilator.jpg
     

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    Last edited: Oct 25, 2019
  13. honegod

    honegod [H]ardness Supreme

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    "typically"

    Why ? Because it is easy ?

    pumping hot air into the case is STUPID ! exactly opposite to what we are after [H]ere.

    The job of the case is to provide mounting points for all the stuffing you want to fill it up with.

    It is the job of Fans to remove heated air from the case.

    Nope.

    An airplane wing is an air deflector.
    A fan blade is too.

    A hovercraft skirt is a duct.
    As are the AC vents in your car.

    Ducts & deflectors are Tools to be used intelligently or witlessly.

    Ducting heated air directly from the heat source to an case exaust fan seems to be a very good use case.
     
  14. doyll

    doyll Kyle's Thermocouple is HOT

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    Good discussion, but not all actually how airflow works on wings, impellers and deflecters.

    What Brian B said is the way it works.

    HSF's job is to move air though cooler. Case fans' job is to move air into, through and out of case.

    The job of fans, all fans is to move air, not heat. We don't 'pump heated air into case. Heated air is what is what comes out of component coolers as they remove heat from component cooler is being used on.

    True about job of case. Case is also used to mount fans to draw air into case and thus push it toward exhasut vents. Exhaust vents usually do not need fans .. same as coolers & radiators don't need pull fan when they have a push fan on front. Push/pull on cooler/radiator/case is only go for about 1-2c with fan at same speed. Single fan running 50-100rpm faster gives same temps as push pull, and as most of us never or extremely rarely run our fans at full speed intake/exhaust and push/pull is not needed.

    No, an airplane wing is not a deflector. Neither is a sail. Wing is designed to create lift with different shape on top (lift) side than bottom. Sail works similar with newest tech sails having the shape of a wing with each side having it's own shape, same as wing (& impeller). A fan blade is similar but designed to move air, not lift as a wing does. Also, air speed is the same the length of a wing, while air speed on a fan blade is much slower near middle than near tip with both sides of wing and impeller performing a job, and even though both create a pressure differential, their design is specific to application. A deflector has only one side deflecting, other side does nothing.

    Generally exhaust ducting is not needed .. except maybe a divider between CPU cooler and GPU to keep GPU heated exhaust from moving up into cool air flowing to CPU cooler.
     
  15. honegod

    honegod [H]ardness Supreme

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    Nit picky, it's a fair cop.

    In the case of computer fans, every single fan has the sole function of moving heat out of the case.
    That's it, nothing else.

    The CPU heatsink is just a heat transfer device, to transfer heat from hot silicon in to hot air.
    In water cooling The radiator has fans to blow the heated air directly out of the case.
    In air cooling however the heated air is just dumped into the case and ANOTHER fan is tasked with exausting air from the case.
    The point is NOT airflow through the case The point is moving generated heat out of the case.

    Ducting airflow through the HS and directly to a "case exaust fan" is the best, easiest, most effective way to do that.

    A airplane wing is 2 diverters bolted together, top & bottom. each shaped to augment the other in their combined function. Yay Bernoulli !
     
  16. doyll

    doyll Kyle's Thermocouple is HOT

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    You are assuming radiator will be mounted as exhaust. Many AIO/CLC users mount them as intake .. and are usually only using them on CPU not GPU as well. GPUs are horrible about dumping their heated air everywhere, which is why I always tell users to remove all PCIe back slot covers to gain more exhaust venting around GPU to improve front to back airflow and thus move the heated air dumping out of GPU back and out better.

    t's not just heat removal or just airflow, it's proper airflow removing heated air as wekk as supplying cool air. I case has good airflow (front to back is usually best) (usually using good pressure rated front intakes & maybe bottom) with both component and case fans sync'ed so case are moving a little more air through case than CPU and GPU coolers so heated component air is moved out without mixing with cool intake airflow almost always gives lower cooler intake temps and thus lower component temps.
     
  17. honegod

    honegod [H]ardness Supreme

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    I apologise.

    This thread is for the folk who WOULD mount an AIO radiator fan as intake.

    Because ignorance.

    Which you are working to fix.
    And my posts here are not helping.
     
  18. doyll

    doyll Kyle's Thermocouple is HOT

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    Your posts are fine.
    It's hard people educated in a field to read a guide written for beginners without finding techical errors.
    Problem is if it's written technically laymen won't understand the principles or skip it because it's too much reading. Many will spend 30-45 minutes watching a talking head who knows nothing video but won't spend 5 minutes to read accurate info.
     
  19. honegod

    honegod [H]ardness Supreme

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    I Thank you.


    ayup.

    A simple mod lets one use a single display to monitor a number of places in the case .

    The lump at the other end of the wire coming from the display box is a "thermister" a resister that changes its resistance with changing temperature.
    Thermisters are cheap and readily available.

    The key is a switch.
    I used the heater fan speed switch from an old toyota.
    What is needed is a switch that has 1 input and several outputs to switch to, the fan switch gave me 3 outputs, low medium and high.
    Allowed me to moniter 3 places in the case just by twisting the knob 1 hard drive array, 2 CPU heatsink, and 3 psu output.
     
  20. bagelnagel

    bagelnagel [H]Lite

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    OK, a question. I have a Caselabs Bullet H7. It has room for 2 120mm fans on the top. I'm using them as exhaust fans, with the stock AMD cooler (Wraith Prism, I think it's called). 2 120mm fans in the front as intake. So cool air comes in from the front, hits the cooler, gets pushed up and out by the cooler and helped along by the 2 exhaust fans. I wanted to put in a different cooler, but it's limited by height considerably because of the top 2 fans. The question is this: should I use a larger cooler, like a CryoRig H7, with no top exhaust fans? Cool air comes in the front, direct line to the cooler, through the heatsink, and out the back of the case. Or should I use a lower profile cooler, and keep the top 2 exhaust fans?

    You can see how the case looks here.
     
  21. honegod

    honegod [H]ardness Supreme

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    From my perspective I would flip the front top fan into intake and block off the rear fan opening
    There are lots of exaust vent holes.

    With the top 2 as exaust lots of the intake fresh air from the front 2 intake fans is just getting sucked right out before getting to do anything useful.

    If you are into modding you could create a duct from the CPU heatsink streight up to the rear top fan and run it as exaust even though there will be some mixing of CPU heated air and the intake air about to be blown into the case by the front top intake fan.
     
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  22. bagelnagel

    bagelnagel [H]Lite

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    The only problem with that setup is that with those fans, my options for CPU coolers are limited because of a lack of height. I'm right there with you on having a positive pressure case (I have 2 80mm fans at the bottom intake). I will also be using filters because I don't want to have dusty components after a short while.
     
  23. honegod

    honegod [H]ardness Supreme

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    What we have here is
    Yup.


    1] remove that rear top fan and bolt on a .5mm sheet of titanium = gooder clearance for taller heatsink with fan on the side blowing at the rear exaust venting instead of up or down.

    OR

    2] remove the HS fan, allowing the top rear exaust fan to take its place by using a duct.
    Best HS would be one with "C" shaped heat pipes so the fins point up towards the fan, lots of heatpipes, lots of fins.

    (titanium because Caselabs, 1mm magnesium would be also suitable)
     
  24. doyll

    doyll Kyle's Thermocouple is HOT

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    Bullet H7 is no a conventional case, and guide in opening post is for tower cases.

    As flat CPU coolers almost always have fans pushing air toward motherboard in your case a top intake in vent over CPU will move cool air from room directly to cooler.

    With only 146mm CPU clearance there are few tower coolers that will fit and cool much better than stock cooler if stock cooler is getting cool air. I would try a top intake with duct over cooler, maybe an intake fan in other top vent. GPU will benefit from intake vent on that side in place of that side window .. if your H7 has window there change it to intake vent with duct to GPU. I would monitor air temp into CPU and GPU to be sure the are getting air at or near room temp.

    Unless stock cooler fan can be turned over so it's pulling air from motherboard through cooler a top exhaust with duct over it will be pulling air away from cooler fan that is trying to push same air into cooler.

    Where is the air your 2x 80mm bottom compartnment fans is trying to move out coming in? For case fans to move air out they need same or more vent area to get air in .. same applies to fans moving air into case needing same or more vernt area for air to get out. What comes in must go out / what goes out must come in. ;)

    I wouldn't block any vents and just let them move the air fans are moving in / out. All of my builds in last several years have no exhaust fans, only intakes. Using both intake and exhaut fans on case is like using push/pull on coolers or radiators. A couple degrees lower temps that running fans 50-100rpm faster gives same temp .. and I never run my fans at full speed anyway.

    Most tower coolers using 90mm fans will fit. If you measure from surface of motherboard to case and subtract 8mm you have actual CPU clearance. If you have 150mm instead of 146mm spec I can think of several coolers to choose from.
     
  25. bagelnagel

    bagelnagel [H]Lite

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    Wow, I'm dumb. I thought that the stock cooler was pushing air away from the MB, up and out from the CPU, not down. Yeesh, at least I'm learning something through this.
     
  26. bagelnagel

    bagelnagel [H]Lite

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    So taking a look at the case, the 146mm is the max height of the cooler *without* any top fans. So the two options are:

    1. No intake top fans, and just the 2 120mm front intake fans. A cooler like the CryoRig H7. Would have a front to back airflow.

    2. 2 top 120mm intake fans, as well as the 2 120mm front intake fans. A low-profile cooler like the stock AMD Wraith.

    Oh, and the 2 80mm bottom fans are intake, not exhaust.
     
  27. doyll

    doyll Kyle's Thermocouple is HOT

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    LOL, we all learn more every day. :D Every system with flat cooler I'ved ben able to switch fan from toward mobo to away from mobo gave me 5-9c cooler CPU temps. When I check air temp into cooler each way the air flowing over motherboard up into cooler was also 5-9c lower temp. ;)
     
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  28. bagelnagel

    bagelnagel [H]Lite

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    Right, that makes sense. So, looking at pcpartpicker.com, I see 2 horizontal flow CPU coolers that will fit the Bullet BH7 case, while still allowing for 2 120mm top intake fans:

    Noctua NH D9L
    Noctua NH U9S

    And if I went with the bottom-to-top CPU coolers, I'm looking at using the 2 top 120mm fans as exhaust:

    Noctua NH C14S
    Noctua NH L12S

    Thoughts?
     
  29. doyll

    doyll Kyle's Thermocouple is HOT

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    If stock cooler is too hot/too loud, NH-D9L is better than U9S. NH-C14S is probably a little cooler/quieter but harder to supply cool air to if not in case similar to what you now have.

    If you could get one, the new Silver Arrow 130 it is twin tower only 130mm tall (120x101x130mm) with 120mm fan and 6x 6mm heatpipes compared to D9L 4x 6mm heatpipes or U9S 5x 6mm heatpipes.

    As I said before, if case spec of 146mm is 3-4mm conservative and you actuallly have 149-150mm CPU clearance there are better coolers .. like Scythe Fuma & Fuma B @ 149mm tall, Thermalright Macho 120 Rev.B and others I can't think of right now.

    Edit: Another is Alpenfohn Atlas 105 x 140 x 125 (W x D x H) with 5x 6mm heatpipes and two 92x25x95mm fans
     
    Last edited: Nov 4, 2019
  30. bagelnagel

    bagelnagel [H]Lite

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    146mm is the height specified by Caselabs - but that is *without* any fans on the top. So the only fans would be front intake fans. Do you think that a larger cooler and just 2 intake fans is better than 4 intake fans, and a lower profile cooler (the question of whether to go with a horizontal or vertical cooler is another consideration)?
     
  31. DoubleTap

    DoubleTap 2[H]4U

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    Since we're being nitpicky, I'm not sure that a water to air comparison is the best as water is not compressible but air/gas is.

    I know we're not doing any real air compression in a PC, but fluid dynamics and aerodynamics are different.

    Also, you don't need the same size exhaust as you to intake, but if you try to exhaust through a smaller opening, then what you are exhausting has to either speed up (uncompressable fluid) or compress (gas) or some combination of both (gas). See venturi / lift / etc.
     
  32. doyll

    doyll Kyle's Thermocouple is HOT

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    Indeed Caselabs says 146mm, but I have built more computers than I can count, many with coolers with specs taller than case CPU clearance spec by 3-5c taller than what case spec said would fit ..in fact I have never had a cooler 3-5mm taller than case spec that did not fit. Which is why I asked you to measure so we have the actual measurement and not just what case company says.

    Get off the air to water comparison and look at definition of fluid dynamics: "In physics and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids—liquids and gases."
    https://www.google.com/search?ei=nX...hUKEwjGpvvlptHlAhV0t3EKHYWICW0Q4dUDCAs&uact=5

    Hopefully that definition helps explain why I keep using flowing water as a comparison for airflow.
    Exactly! Here we are dealing with fluid dynamics, not aerodynamics.

    We need exhaust venting to flow air out out case with little to no resistance.
     
  33. DoubleTap

    DoubleTap 2[H]4U

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    If you're going to play definition lawyer, you should have pointed out that aerodynamics is a subset of fluid dynamics.
     
    Last edited: Nov 4, 2019
  34. doyll

    doyll Kyle's Thermocouple is HOT

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    Not being 'definition lawyer 'at all. Simply pointing out that the science of airflow is called fluid dynamics so comparing flow of water to flow of air is reasonable. Definition quote is what it is .. and it didn't include aerodynamics. Besides, this thead is about case airflow not flying cases. ;)
     
  35. honegod

    honegod [H]ardness Supreme

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    It is about flying heat though. :)

    For this guide water is a good visualising choice, the reaction to pressure is not significant for our needs.
     
  36. bagelnagel

    bagelnagel [H]Lite

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    So I decided to go with 2 top internal 120mm fans, going with slim Noctua's. And going with a horizontal flow CPU cooler, Noctua NH U9S with an additional fan to have push/pull on the CPU cooler. I think it'll have the benefits of increased positive pressure and not having a great deal of hot air hitting the motherboard.