The importance of Airflow in high performance PC modification

Hello everyone, I recently completed a paper on case cooling for my class. I figured I would share it (Be warned parts of it are dry):


            Imagine for a second the computer of your dreams.  Imagine the amazing design, the outstanding power, the epic power behind it and you sitting in front of it playing the most advanced game of the day.  This level of control over the power of a computer so powerful is only a dream for many.  They consider it a passing fancy, and continue about their daily lives without the care of what they are missing.  Many people have even gone as far as creating their own computer from select parts.  I have done this many times, and each time was fun.  A select few go beyond the rank and file to make their dream computer become reality. 

            6 years ago, I received a bonus at work.  This bonus was about $3,000, and I was determined to make my dream computer with it.  I found the most advanced components of the day, which didn’t break my budget of course.  Then, I decided to go off the beaten path.  I wanted to make my computer liquid cooled.  This brought my project into a whole new level.  I did a lot of reading to make sure I knew what I was getting was what I wanted.  Upon receipt, I put it all together, and I realized that setting this computer up would be entirely different from what I am used to.

            Being liquid cooled, I found the installation of the cooling components to be very complex.  Each piece had to be measured and cut exactly, or else I would have to buy more tubing.  This was fine as I am very decent when it comes to measuring components, but what really hit me was that the components required specific voltages which are not the default for the system.  This actually took me over a week to figure out.  I thought I had received bad components.  Once that was completed, I was able to look at my hulking beauty, and say “I think we are ready for the gaming.”

            I believe now is a good point to mention that the laptop I am typing this one outstrips that computer by miles and cost so much less it is embarrassing.  I want to bring this all to the point that between the cost, the frustration and the complexity of design, I enjoyed putting together that computer more than any other I have had before or since.  This more than anything else, got me interested in modifying high performance computers. 


            Modding as high performance PC modification is typically called, can be done for a number of purposes, but predominantly it is for aesthetic pleasure.  Many people want a unique computer which stands out.  Sometimes it is as simple as etching a window with acid.  Other times it could be as complex as making an entirely custom case with laser etched sides, and custom painted exterior.  In each of these cases, the artistic quality brings modding into a league of its own. 

            Another common reason for modding, which in my personal opinion is almost comparable to that of the aesthetic beauty of modding a computer is the overclocking of the computer’s components to make them faster.  In this, I believe that many modders, or individuals who mod, focus on some of the basics that those who only do it for purely aesthetic reasons forget.

            Regardless of the reason of your modifications, the end result has to be a working computer or you are just making junk art which no one will want.  I believe that for a mod to be successful the modder must pick out compatible special purpose parts intended for the end use of the system, and the importance in air flow in thermal dissipation should be emphasized during the creation of the modification.

Airflow is King

            While researching the topic of air flow in regards to high performance computer modifications, I found it necessary to cover the basics of air flow in computers first.  This actually led me to find out several very important tidbits of information myself which I had never known before.  Even with the server I just built only weeks ago had flaws I was never aware of, now fixed of course.  I found that airflow in computers breaks down at several points.  Of these I hope to highlight the most important. 

What Comes In Must Come Out

            This seems like a no brainer, but it really does all come down to this.  Every system must have a way for energy to come in, and energy to leave.  The first law of thermodynamics states energy is conserved; it can neither be created nor destroyed. Our systems are consistently being supplied with an excess of energy into components which despite their technological excellence, are not perfect.  Energy is lost through resistance into heat.  This leaves us with an inevitable conclusion.  We have to get the heat away from our components.  To do this we utilize such devices as fans, radiators, water cooling and phase change cooling. 

Fans and Radiators

            The latter two aside for the moment, let’s focus on fans and radiators, also known as heat sinks.  Heat sinks are a means to draw heat away from a component through thermal transfer into metal fins, which increase the surface area with the air.  Because there is more surface area, more heat can be dissipated quicker. (Robert Hartle, para. 2).  For some of the more advanced and smallest components, this is more than enough.  However, more than often this is not enough.  Modern CPUs for desktop computers require heat transfer which require not only a heat sink, but also a fan.  Fans force air over a component, or set of components to draw heat away quicker. 

            Many people will assume that more fans automatically means better air flow.  This just isn’t the case.  This is because as P1nnacle (2013) puts it so succinctly “More fans give you more potential generators of turbulence, which can keep hot air from going where it should, lingering in the case instead of leaving.” (para. 14). Instead of focusing on having more fans, you should focus on moving more air, more efficiently with larger fans. (Jeff Checchi, 2013, Para 3)  However, to focus solely on the size or speed of your fans ignores a very important point.  No fan, no matter how good will cool your system if it is blocked up with useless wires and dust.

Dust and Obstructions

            Jason Imms (2012) elaborates on this subject in his article on air cooling.  He points out that dust can diminish the air flow and kill your system. (para. 16)  This is where it got complicated though as I found that there is two competing methods of cooling your system.  Jason Imms states very intuitively that “matching the CFM of your intake fans to your exhaust fans is not the best method for air cooling.” (para. 12)  The two methods each have their own benefits and drawbacks.  Table 1 describes the benefits and drawbacks of the positive pressure system while Table 2 describes the negative pressure system.  However, the method you use is solely dependent on your situation. 

Table 1

Benefits and Drawbacks of a Positive Pressure System



Gaps in case contribute to cooling

Graphics card with Direct Heat Exhaust systems will partially counteract the effect

Less dust will get into the case

Average cooling performance compared to negative pressure system

Better support for graphics cards with passive cooling systems


(Jason Imms, 2012, para. 14)



Table 2

Benefits and Drawbacks of a Negative Pressure System



Good Cooling Performance

Dust is more likely to gather in the system as air is drawn in through all openings

Amplifies natural convection

Passively cooled video cards do not gain much benefit

Linear and direct air flow


Compatible with DHE graphics cards


Augments the performance of downward facing CPU heat sink fans.


(Jason Imms, 2012, para 15)


            The other major factor you have to consider when managing the airflow in your case is the flow path.  Cables and wires provide blocks for your air flow, and provide an anchor for dust to accumulate on.  This brings up the point of component and cable management.  When creating a system, selecting the best components can sometimes involve thinking about how they will affect your air flow.  A graphics card, for instance, typically comes with its own fan and air flow system.  In many cases, this is a god send, because the GPU can produce a lot of heat, however it can easily become a problem.  This is because, as P1nnacle (2013) explains, the flow of air on a graphics card can have a negative effect on the pressure of a case, in many cases affecting the cooling capacity of the card. (para. 5-6).  With that being said, do not immediately dismiss a graphics card because it has a cooling system that does not compliment your case. Instead, consider modifying the air flow system of the fan to the point where it compliments it.

            I also found that cables themselves can be a hazard to heating, and this is problem that many modders will appreciate.  A good looking case, is one with excellent cable management.  No one wants to see an amazing Metal Gear Solid case with cables everywhere which just look like a mess.  Instead solutions do exist for this.  The primary system I have seen is through limiting the cables your system has.  Modular power supplies are an excellent option for a modder with cable management issues.  Why do you need 15 molex connectors when you only use 2?  Those 13 other cables are just sitting around wasting space, and blocking air flow. 

            “But I need that super wambodine triple laser powered cooling fan for my memory!”  This is a struggle as components are becoming more and more powerful and producing more heat every day.  Cooling solutions exist for every piece of it.  In actuality you should consider not using some of the more expressive components unless absolutely necessary to allow your case to provide cleaner air flow.  Placing a fan in the center of your case which goes against your air flow can seriously impact your air flow and in the case of hard drives they were built with passive cooling in mind from their inception (Henry Winchester, 2012, para. 18).  I believe Jason Imms (2012) put it best when he said “Remove those old PCI cards that never get used anymore, leave the RAM module extra fan kit in it’s packaging, and… [p]lease, throw away your floppy drive.” (para. 9). 

Water and Phase Change Cooling

            Components won’t matter if you have phase change cooling, you can super cool your computer, and really air flow at that point needs to be minimal if not just ambient.  However, if you haven’t noticed lately, phase change cooling is super expensive and reserved for only the extreme modder.  That being said, what about water cooling.  I know many people have done some form of liquid cooling for their computer.  There are many pros and cons, however the meat of it comes down to that Water Cooling is not a replacement for fans in their entirety.  Water Cooling requires a radiator, or water heat sink, which fans are used to cool.  I bring this up because the idea behind proper air flow is not just to cool specific components, but the entire computer. 

            Your motherboard, even the parts no one ever looks at, produces heat which has to dissipate somehow.  A mistake which P1nnical (2013) points out is that you shouldn’t just place your radiator at your intake. (para. 3).  The reasoning behind this is simple.  If you have air coming in to cool your minor components as well as your radiator, your radiator is taking care of the major components.  If the air passes through the radiator removing heat from the major components, it will then blow that hot air over the remaining pieces of your computer, raising the overall temperature of your system. (para. 3) 


            Throughout the course of my research, I found one fact exceedingly clear: airflow management as a whole is much more complex than I first thought.  By the nature of their job, most computer technicians are not scientists.  This leads to a reliance on outside sources to obtain information such as how heat transfers from one object to another.  To put it plainly, the modding community does not sit there and do math to find the perfect ratio of fan speeds, and placement.  They do things the “hard” way, and place fans in different configurations to see how it affects their system.  To put this into perspective, I did a search for a form of modeling software which could allow me to test airflow and heat transfer in an enclosed environment, but could not find any.  The complexity of the math behind it is obscene.  So are modders wrong for doing things the “hard” way?  No.  In fact, until a method which can easily test air flow and heat dissipation for different PC configurations comes around, the “hard” way is the best way. 

            Another major thing I found was that even though the resources are out there to help with airflow, a vast majority of computers are not built following these simple guidelines.  A good example was how we recently processed a batch of dell computers for disposal, and every single one of them had a duct blocking the external fan, and only outlet of air for the system.  This is compounded by the fact that there was no cable management, and there were extra components not actually hooked up to the system.

            In conclusion, I found that regardless of whether you are a modder or just an everyday technician, purchasing of only the parts intended for the end use of the computer, and stressing the importance of airflow for the purpose of thermal dissipation while building a computer is paramount.  A computer can be an investment costing over one thousand dollars, by keeping it cool, and uncluttered, you can increase the yield of that investment by magnitudes.


Checchi, J. (2013, October 23).  How to Build a PC – Selecting Case Fans.  Retrieved from


Hartle, R. (n.d.). How Heat Sinks Work.  Retrieved from


Imms, J. (2012, May 3). ExtremeTech’s guide to air cooling your PC.  Retrieved from http://


P1nnacle (2013, October 28).  Airflow 101: Setting Up Your Fans and Keeping Your Computer

            Cool.  Retrieved from


Winchester, H. (2012, April 15). How to optimize your PC’s cooling.  PCFormat Magazine, 264. 

            Retrieved from



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