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post #5 of (permalink) Old 05-26-2014, 05:34 AM - Thread Starter
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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.
  • 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.

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 one part. All openings not covered by intake fans in front and bottom of case need to be blocked so the air fans push into case has to move through case, not leak back in front of fans. I've found I rarely need exhaust fans. Good pressure rated intakes are usually all that's needed.
  • 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
  • My 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.
  • Clip and position sensor where I want to check the temp. Make it easy to see what the air temp going into components actually is relative to room temp.
  • Optimum cooling is when air temps going into coolers only being 2-3c warmer than room.. 5c or less is good.

Phanteks Owners Club Ways to Better Cooling
i7 980 @ 3.55GHz =PH-TC14PE w/2x TY-143 fans =Crucial Ballistix 3x4GB =GA-X58A-UD5 =ASUS GTX580 DirectCU II =Enermax Modu84+ =Define R2 w/3x TY-140 case intake fans; all PWM controlled by CPU fan socketPhanteks Enthoo Primo MoBo Rampage III Extreme CPUi7 980X
@ 4.0GHz =R1 Ultimate w/2x TY-143 fans =Dominator GT 6x2GB =Rampage III Extreme =ASUS GTX580 DirectCU II =TX850 =Enthoo Primo w/ custom castor base

Last edited by doyll; 01-15-2020 at 06:28 AM.
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