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Vertical vs. Horizontal Case Cooling

Written on August 9, 2011 by Matt Bach


Exceptional airflow is something that is essential for a cool-running computer. Traditionally, computer cases are oriented with the air intake in the front of the case and the exhaust in the rear. However, some manufactures have lately been orienting their cases 90 degrees from the norm with the air intake at the bottom of the case and the exhaust at the top. The theory behind this design is that since hot air rises, having the airflow in a up/down orientation allows the case to work with, rather than against, the forces of convection.


Our main question is: does a vertical airflow in a chassis improve cooling? To answer this question, we will separately test two chassis in both vertical and horizontal orientations. Although we will be testing multiple chassis, it needs to be clear that we will not be directly comparing the chassis against each other. What we want to find out is if having an up/down airflow alone really makes a difference, not whether one case or the other has better overall cooling. Vertical cooling cases have a vastly different internal layout than traditional cases, so we will be using both a traditional cooling case as well as a vertical cooling case for all of our testing. The two cases we will be using are the Antec P183 V3 (traditional cooling) and the Silverstone FT02B-W (vertical cooling).

The Antec P183 V3 has a more restricted airflow and caters more towards quiet operation. The Silverstone FT02B-W has very low restriction on airflow, which is great where noise is not as much of a concern.

All of the components we will be using for testing are high-wattage parts with very high thermal outputs. This means that some of our testing may give us temperatures that are much higher than what we would normally deem safe, but temperature variances should become more pronounced by using these very hot components. It needs to be noted that realistically we would never have these components in the Antec P183 V3 with the fans on low. We would normally either turn the fans up or mod a side fan into the side panel so that the case would provide adequately for all the components. For this testing, we actually want the case to be running very hot with low airflow to ensure that any forces of convection are not overrun by high-flow fans. We are trying to represent both ends of the cooling spectrum and these two cases are almost the embodiment of high airflow, and quiet cases.


Both cases will be setup with the stock case fans running at their lowest settings. All testing will be done with both a traditional air-cooling CPU heatsink (Gelid Tranquillo Rev2) and a closed-loop CPU liquid cooler (Coolit ECO II). Normally we would configure the Coolit ECO II as an intake in the Antec P183 V3, but in an effort to "work with convection" when case is turned on its front, we will be leaving it in the default exhaust configuration. This will raise the CPU temperatures on this cooler, but is more appropriate for this comparison.

Temperatures will be examined at both idle and load, with a combination of Prime95 and Furmark used to put both the CPU and GPUs under full load for 10 minutes. Temperature recording will be performed with Coretemp and GPU-Z, as well as with a thermal imaging camera. A controlled environment with an ambient temperature of 24 Celsius will be used for all testing. The margin of error for our temperature readings is 1 degree Celsius. There is a margin of error for the thermal imaging as well, but as we are looking at images and not hard numbers it is very difficult to define. We will be relying on our years of experience working with thermal images to determine which variances are worth pointing out and which can be attributed to normal testing fluctuations.

Testing Hardware:


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Could you just test the same case normally, and then again rotated 90 degrees to see any impact on connection. you could, just for fun, rotate the case 90 dagrees Ge other way to see if forcing the air down makes any difference.


Posted on 2011-08-10 15:52:55

Ben, that's a very interesting idea.  We tested with a 90 degree rotation...why not a 180 degree rotation?  Vertical cooling vs anti-vertical cooling!  We may just have to try that.

Posted on 2011-08-10 16:05:53

Haha, I agree with Ben's idea. You should definitely try that one guys...

Posted on 2011-08-10 17:48:56
Mike Rudziensky

Just wanted to chime in and let you know these articles are awesome!

Posted on 2011-08-10 17:55:24
Bob Sadler

These tests have got me actually thinking about what you expected the results to be and what the results actually were.

The idea that the Vertical Case should do better with cooling relies upon the idea that hot air rises, and while this is true, if the hot air has no inflow of cooler air, it's not going to rise all that fast.  Hot air rises, albeit slowly, but put a fan at or near the bottom of your Vertical Case to draw the cool air in, then the hot air will be pushed out by the cool air rushing in.

When I thought about this with my own System, a Vertical System, I thought this was a no-brainer that the heat should just rise up and leave, and while that's exactly what will happen, if there's no air coming into the case, there's nothing to push the hot air up and out.  If anyone has ever been in a church on a 110 degree day, you know full well how this works, especially if the Church was built before the advent of Air-Conditioning.

I would like to see what results you would get if you added a fan at the bottom of the Vertical Case that would draw room temperature air into the case, which should then push the hot air up and out, at least up, closer to where the top fans are, which then pull it out.


Posted on 2011-08-10 21:29:07

Very similar results to my own test review of the silver model. The unrestricted airflow does more for the components than fan power. However, convection is still a very important principle to consider in all computer cases. In
vertical computer cases, it's extremely important that the design of the case create a bit
of a wind tunnel for optimal results. In other words, cool air should
get pulled in through the front, efficiently reach the
motherboard area cooling components and finally be expelled out of the top or back of the case.

A very good indicator of optimal airflow is AMD's retail CPU cooler. (I use a very hot and potentially loud AMD test system to measure thermal results as well as any noise blocking properties which have great value. No one likes an audible tin-can system.)

If too much air gets expelled out through the top of the case, the cool air coming in through the front will be drawn to the top of the case before the cool air gets to motherboard area. In this instance, the retail cooler got louder. The Antec DF-85 case is one such case that performed better with the top holes blocked off. Even with the case fans on high, the retail CPU cooler got quite loud. The rear fans did the proper job of creating the wind tunnel.

Another good example is what Puget Systems does to the Antec P183. You typically cover the top fan vent with sound dampening material because it creates a better wind tunnel and eliminates a little more noise. The secondary internal HDD bay mounted fan is very handy helping push the cool air to the back.

With that said, it's ultimately not the number of fans you have in the case, but how they are configured creating as much unrestricted the air flow as possible coming in from the front (as with the Antec P183 case) or the bottom (as with the Silverstone Fortress 2). 

Posted on 2011-08-11 04:23:59

Thank you for an excellent article. I have often wondered about the placement of intake fans in typical (horizontal) tower cases. In a normal case, air comes in from the lower front and out the upper back with the intention of passing over the main components (GPU, RAM, CPU). But first it has to get through the block of hard drives. And then it has to get past a long graphics card which usually divides a case into 2 areas and directs most of the airflow towards itself.

Perhaps it is time for horizontal cases to abandon some of the front 5.25" bays and put another intake fan in, purely to cool the CPU area of the motherboard. For example, in a typical row of 5 external drive bays, you could replace the middle 3 or upper 3 with a 120mm intake fan. Who says the DVD has to be in the top bay? And what are 5 external bays used for anyway? This would effectively create the same direction of unimpeded airflow that the Silverstone cases enjoy, but in a horizontal case.

Posted on 2011-08-11 13:49:54

Confirmed points there Denis. I would like to see a case that has configurable 5.25" and 3.5" bays. In other words, designed in a such a way I can remove 2 at a time versus the usual whole tray such as things are with the Antec P183 case. Case manufacturers have the ability to get innovative like this. They just need motivated.

Posted on 2011-08-11 19:06:03

Great article!  Can you please also comment about the sound of the Silverstone case?  I know the article was on cooling, but I was curious about how quiet the Silverstone case is with the large fans.  From the reviews I have seen, it looks like it would be pretty quiet.  Also, any thoughts on the size of the case as compared to the Antec.

Posted on 2011-08-11 17:45:48

Silent PC does great reviews with an emphasis on noise levels, and they have a review up for the FT02 (empty case, no hardware).  You can see the noise results here: http://www.silentpcreview.c...

Unfortunately, SilentPC hasn't reviewed the P183 case alone as far as I could find, but they have reviewed our Serenity PC's, which use the Antec P183 V3.  You can see those results here: http://www.silentpcreview.c...

To summarize, the FT02 was 19-30dBA depending on fan speeds, and the Serenity was 11-12.5 dBa depending on system load.

Now, this is not a true comparison, since the Serenity had quieter fans installed, but that brings up another point that we didn't really touch on:  It is fairly easy to find quiet versions of 120mm fans since they are pretty much the industry standard today, but it is much harder to find quiet 180mm fans. 

To summarize, the FT02 is definitely louder than the P183 V3, but since we put a large emphasis on quiet operation, we are also much more picky than most other manufactures. 

Posted on 2011-08-11 20:08:48

SilentPC did test a RV02 (which is very similar to FT02) and has direct comparison chart showing how it compared to other cases including P183 when using a multi GPU setup:

Please keep in mind that this SilentPC test was done before we upgraded RV02 and FT02 with the newer AP181 fans in 2010.  So the performance gap would widen even more if they are repeated again.

I am sure Puget could create an awesome setup with a FT02 that can be both cooler and possibly quieter than what they could do with the P183!  :-)

Posted on 2011-08-12 07:47:47

The Silverstone Fortress 2 is 19.5" tall x 8.3" wide x 24-1/4" long (deep). This is a really deep case and may not fit inside your lower desk cabinets. Make sure you have the cabinet depth if that's where it's going. The FT02 is 4" longer (deeper) to make room for those 3 x 180mm fans.

The Antec P183 V3 is 20.25" tall x 8.1" wide x 19.9" long (deep). It'll fit in your average cabinet. Don't forget to account for wiring.

Speaking of FT02 noise, the fans are rated to 27dB(A) max but that's based on measuring the stand alone fan. Inside the case, the fans are much quieter (about 17dB) measured from the side partially due to the sound dampening properties of the case. The window model lets just a little more noise out. However, the fans can be throttled back a bit more and the case will be very quiet.

It's also worth noting that any fan noise escapes the FT02 at the top of the chassis as it's the only vented area while any noise escapes the back of the P183 V3. If the FT02 is placed anywhere near floor level, you can hear a retail cooler from the top. If the P183 V3 is near a wall, you'll get the noise bouncing back a bit. I recommend a good aftermarket cooler like the Gelid, NZXT Havik, Noctua air coolers, or liquid Kuhler units to remove that possibility.

Hope this answers the question.

Posted on 2011-08-11 20:46:16

If you're going to do vertical cooling, add a chimney!  Adding a chimney increases the volume subjected to the bouyancy effects while leaving the horizontal surface area intact, which should increase the pressure involved.

Posted on 2011-10-09 02:02:59
Paul Uszak

I'm trying this right now. I'm doing some steampunking of a new pc and will be adding a chimney to the top of a mainly enclosed wooden case. The whole bottom of the case will be open, and I'm trying a first guess at chimney height of about 400mm.

Posted on 2014-11-17 04:02:03
Ben Wetherbee

More testing should be conducted here. 

Most mainstream horizontal cases actually concede that vertical dissipation is advantageous... the top exhaust. 

Take a case that does not have a top exhaust and run the same comparison.  I am willing to bet that it will cool better when flipped to a vertical position.  Also, there are a plethora of other factors that should be considered here.  A negative pressure horizontally-oriented case was tested against a positive pressure vertically-oriented case.  In regards to negative and positive... it will make an impact in regards to GPU cooling and also the design of the GPU's cooler.  Does the GPU cooler push air out the back of the case or does it blow air in BOTH directions (in and out).  This small test simply doesn't make a strong argument to which orientation actually performs better.

Posted on 2012-05-14 18:17:52

Maye this article is why even cases with bottom mounted PSU's still have the traditional front and rear intake ports

Posted on 2014-04-03 15:18:14

sorry meant intake and exhaust

Posted on 2014-04-03 15:19:10

Do you think you could retest this with the Silverstone FT05B and modern hardware?

Posted on 2017-03-14 18:21:44

This is a very old post but I felt like I had to say something.

This experiment is totally flawed. You've got hundreds of experiments in other fields that illustrate the opposite result. You think that there is something special with computer cases? In actuality, this experiment illustrates the phenomenon that there are so many factors in real life situations that theoretical tests may not capture all the significant factors in play. In this experiment, most likely certain obstacles were in the way that skewed the results in the opposite direction.

I bet if you took the horizontal air flow configuration that produced the most heat loss, simply turned it 90 degrees and compared the difference, you would see that the one with air flow from bottom to top produce more heat loss.

The problem with modern computer cases is that manufacturers appear to have zero knowledge of fluid dynamics. For example, having any holes along the side of the computer case does NOT help with heat loss but has a SIGNIFICANT negative effect on heat loss. It seems nonintuitive but the air in and out substantially disrupts smooth and efficient laminar air flow. You want to first achieve the maximum LAMINAIR air flow as possible by minimizing osbstacles and things like holes. Only then, can you increase turbulence which leads to higher absolute but more inefficient cooling.

Do this experiment if you don't believe me. On a very hot day, don't open all the windows in your house. This is actually the very WRONG way to cool your home. Instead, open one window(s) on one side and then open window(s) that lead to the straightest possible line to the other side of the house. Keep all the other windows closed. You'll actually feel a cool breeze. But if you open all the windows, the house will stay hot. The reason is that a laminar air flow is not established when the windows are all open.

I still can't believe that computer cases haven't been designed so that air flow goes from bottom to top.

Posted on 2018-07-09 18:13:36

Finally a logical response. Thank you for that clarity. Every time I look at new cases I see them ignore the laws of physics. Maybe they think they are simply above such pettiness. They aren't. None of us are.

Posted on 2019-04-15 20:45:58