DAN C4-SFX - old

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dondan

Shrink Ray Wielder
Original poster
DAN Cases
Feb 23, 2015
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@Nenja:

1) I tested on the prototypes there is no real difference between pushing out at the bottom or top. So maybe there is some reusage of rising air but not messurable.
2) You will have a radiator+fan chamber with 56mm in height where you can put whatever configuration you like
3) Mountpoints for HDPlex will be included
4) The C4-SFX will have nearly the same restriction for the GPU in height as the A4-SFX. So yes very tall cards will fit.
 
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FdeFons

Caliper Novice
Dec 8, 2017
31
9
1080 ti asus strix oc would it fit? It measures 5,25 cm of width and 298 length

thanks for the info
 

Sean Crees

Airflow Optimizer
Jan 1, 2017
352
316
Firstly, I love the original design! Solid work.

  • Pulling from top and pushing through the bottom creates an airflow loop that will work against itself. As the hot air is pushed out the bottom, it's natural tendency is going to be to rise, right back to the top of the case where it's going to be pulled in again.
Convection forces are extreamly weak. They are only measurable when you have zero airflow. Any fans at all will completely overpower any convection force. Working against such a weak force won't have any measurable effect on temps.
 

Supercluster

Average Stuffer
Feb 24, 2016
87
127
Convection forces are extreamly weak. They are only measurable when you have zero airflow. Any fans at all will completely overpower any convection force. Working against such a weak force won't have any measurable effect on temps.

And you say this because... Steve from Gamers Nexus says it?

Anyhow, for anything under 1000 RPM fans, particularly under 800 RPM, convection is very relevant. Every cooling system optimized for quiet (potentially silent for us humans) operation should be designed to work with convection.
Even with faster fans, working directly against convection (upside down) will still cost you a few percent of the performance.

Let me reiterate, Steve does some decent tests, however, in many areas he is very imprecise, like doing watchmaking with a wrench.
Look at some wind tunnel tests (there are even some done by GN), and you can see the smoke rising ever so slightly when the fans blow, for example, from front to back.

This translates to a percentage of lost performance: No matter how small, the slower the speed, the greater the performance loss when working against convection.
 
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FAQBytes

SFF Lingo Aficionado
Feb 22, 2017
91
102
So I'll say this in response to those talking about the effect of convection pressures in this case.

TL;DR - It's negligible.

For those of you slightly more concerned, I'll list out much of the important information as well as some of the summaries regarding the calculations I made. If there is enough interest, I'll post all pages of calculations and corrections.

NOTES: The following was done using rudimentary thermodynamics and physics. As such, the actual figures will be... Off... for lack of a better term. However, these issues will be addressed in the "Corrections" section, that would address the differences between this and the CFD versions of the calculations.


First, the assumptions.
The fans used are the Noctua NF-P12-1300 Redux. These were chosen as a good middle of the line (and not brown) pressure optimized quiet fans. The specs as given are: 1.68 mmH2O static pressure and 0.0513 m^3/s airflow. The internal volume of the case for the purpose of calculations was 10L, or 0.010m^3. Additionally, an 8700k and RTX 2080's power consumption figures were used for the purposes of DeltaTAir, with 95W for the 8700k and 225W for the RTX 2080 (as that is what I will be putting into the case). Other component power dissipation is neglected as this is already a higher TDP than what should be reasonably seen for long duration usage.

The assumptions for actually determining methodology are as follows: DeltaKE=DeltaPE=0, the air is an ideal gas with a constant specific heat (due to low temp difference), the case has nothing in it and no radiators (this gives the greatest % difference, and is just simplest for calculating [If someone wants to give me the static pressure and airflow volume/velocity and area of fans post-radiator, I will be more than happy to revise some things]), ideal fan performance, sea level air pressure, ambient temp of 21C/~70F, and steady state operation. The internal of the case was basically treated as a solid body of constant density, like a membrane holding the air inside of it.

With that said, let's get into calculating.

Airflow and air density at 21C gave a mass flow of 0.06156 kg/s.
Using energy conservation, a DeltaTAir of 8.5089C was given.
For simplicity, I calculated the buoyant force of a body of 10L with the given DeltaTAir between 21C and 30C of 0.03924N, which is the equivalent of distributing 4g across the top of the case. Converting from Newtons to Pascals, then to mmH2O gives 0.0972mmH2O, with a pressure difference remaining of 1.5828 mmH2O.
After iteration, the total efficiency is ~91.5% in terms of pressure, not airflow, which is, by far, the more important measurement.
(NOTE: this is still a pretty unrealistic number for reasons I'll address, not to mention being solid body force analysis)

However, this is not the CFD solution, so I will explain some of the differences:
The uniform air body was treated as a uniform body, greatly increasing effect of convection forces.
Does not account for actual internal volume with components, which would decrease effect of convection currents.
Does not account for actual fan performance curve, which could increase or decrease effect of convection currents depending on the curve.
Assumes fans as solid bodies.
Fans assumed to be in free-stream. Though accounting for radiators and internal solid bodies will greatly decrease air velocity and pressure, it will also greatly decrease the influence of convection forces due to the nature of fluids.

I'm sure that I made a few small errors in places, but overall I would expect the fans to operate with 5% of each other when inverted vs. non-inverted, which amounts to 1-2 degrees Celsius.

I might be able to do CFD calculations through Solid Edge ST10, but that's free time I don't have right now to learn something I'm not entirely familiar with. I'll see what I can do starting next Thursday.
 
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Sean Crees

Airflow Optimizer
Jan 1, 2017
352
316
And you say this because... Steve from Gamers Nexus says it?

Anyhow, for anything under 1000 RPM fans, particularly under 800 RPM, convection is very relevant. Every cooling system optimized for quiet (potentially silent for us humans) operation should be designed to work with convection.
Even with faster fans, working directly against convection (upside down) will still cost you a few percent of the performance.

Let me reiterate, Steve does some decent tests, however, in many areas he is very imprecise, like doing watchmaking with a wrench.
Look at some wind tunnel tests (there are even some done by GN), and you can see the smoke rising ever so slightly when the fans blow, for example, from front to back.

This translates to a percentage of lost performance: No matter how small, the slower the speed, the greater the performance loss when working against convection.


Steve isn't the only one who has tackled this issue. This is something people bring up over and over for years now. I can remember people arguing about this over 10 years ago on the silentpcreview website. Everyone that did actual testing shows the same thing. If you have any airflow from a fan whatsoever, even if its running at a very low RPM, its enough to completely negate any sort of convection airflow. Convection is only something you need to worry about if you are in a completely fanless configuration.
 

Rankless

Trash Compacter
Sep 6, 2018
48
49
Is there any interesting news to share? Is the current work more engineering or soul-searching? Are you confident enough in your current case implementations to post a poll if that is still your current ambition? Case feet or waterblock news :] ?
 
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dondan

Shrink Ray Wielder
Original poster
DAN Cases
Feb 23, 2015
1,977
8,378
I currently work on CAD of the classical design with direct cooled radiator. I think I am 80% done with it so maybe I finish the work this week. I think semi passiv cooled is out of question because I think nearly no one feel the need of 2x 240mm radiator. Therefor I make the decision to move forward with the classical design. Maybe I can show renderings this week.
 

N0_Klu3

Efficiency Noob
New User
Sep 26, 2018
5
0
@dondan whats the feeling on the new NVIDIA GPU's and their width?
Are you going to make adjustments so these fit?
Or whats the plan here?
 

N0_Klu3

Efficiency Noob
New User
Sep 26, 2018
5
0
C4 will support 2.5 Slot GPUs I think this is enough. Every OEM has cards that will fit and also the NVIDIA FE are great too.
I thought the FE were 2.75 slot... Ok well 2.5 is totally doable :)
Thanks man, now hurry up and release it :D
 

Matsu

Efficiency Noob
Apr 15, 2018
6
8
If you put the C4 on your left side on the desk with radiator on bottom with pull you will lose cooling performance because on the small space between bottom surface and case.

I have my case on the left side on the desk, had it so for last 4 years .. almost the only option as the door is on the right side of the desk and if i move my desk to the other wall the sun shines directly on the screen o_O That means when the sun shines here in Finland this time of the year, ehm.. like never :cool:
 

Hudbox

Cable Smoosher
Oct 3, 2018
10
16
I currently work on CAD of the classical design with direct cooled radiator. I think I am 80% done with it so maybe I finish the work this week. I think semi passiv cooled is out of question because I think nearly no one feel the need of 2x 240mm radiator. Therefor I make the decision to move forward with the classical design. Maybe I can show renderings this week.

This is music to my ears.

I look forward to seeing the final render.
 

Matsu

Efficiency Noob
Apr 15, 2018
6
8
@Matsu Then install the fan in push mode, i don't see the problem.

Yeah i know, never said there was a problem, was only mention it.. So there will be no problem when you do the final design of case so you consider every costumers need for cooling options ;) i will probably say goodbye to my Corsair AIO and do a full custom loop in this case!
 
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FdeFons

Caliper Novice
Dec 8, 2017
31
9
C4 will support 2.5 Slot GPUs I think this is enough. Every OEM has cards that will fit and also the NVIDIA FE are great too.

@dondan It makes me happy to listen that you continue for the classic design

I have a asus rog strix 1080ti and this GPU have length 298mm and this case allow GPU up to 295mm
it's possible to lengthen the case for 3 mm?
 

MeltingCake

Minimal Tinkerer
Dec 3, 2018
3
8
Gonna go out there and ask, by "classic design" this is the one with 1rad and is like ~10L?

With the fiasco with the Ghost, very, very excited about this case. Have been looking for something not much bigger than the A4 but with better cooling :p
 

schn1tt3r

Cable-Tie Ninja
Sep 24, 2018
151
247
I think semi passiv cooled is out of question because I think nearly no one feel the need of 2x 240mm radiator. Therefor I make the decision to move forward with the classical design. Maybe I can show renderings this week.

Great news for me! Back to being hyped for this project.

Here is what happens when you cram too much on a tiny case (and this one even has fans)
 
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