Wood/Alum PC Case Build

[illerin]

Current State:

 

 

Original Post: 

 

So i'm planning on building a computer case that mounts under my desk. So the main focus is thin and small so I'm less likely to bump my knees into it. 

Planning on building it later this years after AMD and NVIDIA release whatever next gen stuff they have. Just want to make sure i'm not shotting myself in the foot with a bad area for the layout and config. 

 

Planned config:

-AMD CPU 

-Lower end Quadro Card

-Micro ATX B550

-32gb ddr4 3200 RAM

-SFX Power supply

 

Build Materials

-Kerfed wood sides

-Alum back plate

-Perforated alum bottom plate with alum rim

 

 

Right side item is internet router, center is computer case and left side will be power management.

 

 

With the case mounted to the bottom of my desk, I'm planning on a filter screen sandwiched between perforated metal panel bottom and a wood panel with cutout for where air is supposed to flow.

The CPU, GPU and power supply would be taking in fresh air along with a single 120mm fan, with output holes along the back panel and in the upper corner of the bottom panel. 

 

Thoughts on the layout?(red indicates fans) Still need to figure out how to make a mounting bracket for the GPU, did a simple adjustable one to hold the back end. Also should i make the single 120mm fan push air out? or keep the system with more positive air pressure?

 

 

Edited November 1, 2020 by illerin

[startrek03]

You should add a second PCIe slot, maybe even a third just to be sure, that every GPU will fit.

Otherwise, cabling might be easier, if you swapped the GPU and Motherboard.

[illerin]

yeah, debated on adding a second slot, probably will add that. I don't think i have enough room for a 3rd slot as the graphics card already overlaps the motherboard some still.

As far as swapping them, do you mean moving the mobo to the center and the GPU to the outer side and running the PCIe cable under the mobo to the graphics card? 

[startrek03]

7 hours ago, illerin said:

yeah, debated on adding a second slot, probably will add that. I don't think i have enough room for a 3rd slot as the graphics card already overlaps the motherboard some still.

As far as swapping them, do you mean moving the mobo to the center and the GPU to the outer side and running the PCIe cable under the mobo to the graphics card? 

Ok, I didn't think that through very well...

[burh4n]

On 8/20/2020 at 9:54 PM, illerin said:

The CPU, GPU and power supply would be taking in fresh air along with a single 120mm fan, with output holes along the back panel and in the upper corner of the bottom panel. 

 

So I'll share my viewpoint as an engineer and from my background in physics. The blower style GPU (if that's your plan) and the PSU will essentially act independently, so I think you're okay there. 

From how I read your statement above, the square cutout on the top panel and the perforations on the rear panel will be your only exhausts; which will be passive vents since all fans are pulling air in. Personally, I think you should exhaust using the 120mm fan. Reason being is otherwise the hot air from cooling your MOBO is likely to linger inside the case. I know the arguments of positive vs negative pressures, but in the ideal situation, you'd replace the volume of hot air with cool air at the same rate (balanced input and output). 

 

I know that more intake is supposed to help with dust control, but if you have a filter (which you mentioned) and clean it regularly, you'll be fine. The other argument is that "pushing" the hot air out (positive pressure, more intake) is just as good as pulling it out (exhaust), but there are several reasons why this might not be true: impedance, environmental pressure, vortices, and flow surface areas. 

 

My recommendation isn't to use one way or another, but to experiment with your fan configuration (remember to control your variables). I do believe you'll see better thermals (personally) by exhausting air using the 120mm fan as opposed to using all fans for intake. Post back and share your experience, and definitely share some photos of your build, it looks like it'll be quite nice!

 

 

[illerin]

9 hours ago, burh4n said:

 

 

So I'll share my viewpoint as an engineer and from my background in physics. The blower style GPU (if that's your plan) and the PSU will essentially act independently, so I think you're okay there. 

From how I read your statement above, the square cutout on the top panel and the perforations on the rear panel will be your only exhausts; which will be passive vents since all fans are pulling air in. Personally, I think you should exhaust using the 120mm fan. Reason being is otherwise the hot air from cooling your MOBO is likely to linger inside the case. I know the arguments of positive vs negative pressures, but in the ideal situation, you'd replace the volume of hot air with cool air at the same rate (balanced input and output). 

 

I know that more intake is supposed to help with dust control, but if you have a filter (which you mentioned) and clean it regularly, you'll be fine. The other argument is that "pushing" the hot air out (positive pressure, more intake) is just as good as pulling it out (exhaust), but there are several reasons why this might not be true: impedance, environmental pressure, vortices, and flow surface areas. 

 

My recommendation isn't to use one way or another, but to experiment with your fan configuration (remember to control your variables). I do believe you'll see better thermals (personally) by exhausting air using the 120mm fan as opposed to using all fans for intake. Post back and share your experience, and definitely share some photos of your build, it looks like it'll be quite nice!

 

 

Thanks Burh4n for your input! Will differently have to try the fan both ways and bench mark it once its built. There is a second exhaust under my graphics card, though it will be smaller since i'm going to make a second slot increase i go with a double slot card, but i get what you mean by the mobo just spinning the same air. Was thinking about putting a 60mm fan for a side exhaust by the mobo so the air is drawn across the case. Dont think this would detract from the look of the case and it wouldnt be blowing hot air on my legs. 

 

Made the power strip cable box as a test run for making the case and think it turned out nice. This doesnt have the 1/8" alum trim i intend to put on the case so it does look a little bare. Thinking about getting some self etching alum paint and testing out coloring the alum. 

[illerin]

Question on wiring. Since my computer was under my desk, i was thinking of making a 'remote' wired on/off, reset, power light box that was above the desk(still have  a built in on/off on the front of the case). Was planning on using a usb cable for this, but it doesnt have enough wires unless a combine the GND's. I  dont think that would cause any problems but figured i would ask just in case.

[burh4n]

13 hours ago, illerin said:

Was thinking about putting a 60mm fan for a side exhaust by the mobo so the air is drawn across the case.

Not a bad thought, but might add some noise, definitely look for some quiet fan options there. Also, that might be blowing directly onto your networking equipment right? Just thinking about thermals under the desk in general, and wondering if you'll have enough space between the wall and the edge of the desk for airflow? Your legs might get warm under the desk, especially depending on how tall you are (have you checked to see how much space there will be from the top of your legs to the PC case?).

4 minutes ago, illerin said:

thinking of making a 'remote' wired on/off, reset, power light box that was above the desk

Do you really need the reset button? Personally I'd ditch the reset button and keep only the power light and switch, then a USB cable would be fine. Additionally, you could use some CAT5 cable or even HVAC thermostat wire if you need extra conductors, but I get it if you have a spare USB cable already you don't need to buy cabling. 

[PriitM]

While its not a bad idea to separate individual fans to respective coolers, it is a bad idea to have the internal volume mix. Different sizes of fans, intake/exhaust port sizes, fans speeds and airflow patterns. Plus, a narrow case has a hard time of controlling radiant heat (since mirroring surfaces are so close to the source). All positive pressure would keep hotter air inside the case longer (relatively speaking), allowing radiant heat to build up in the case walls. 

 

I would add partition walls between the different heatzones and have respective exhaust ports for each one. 

 

Blower GPU will handle itself, HDDs (wont get that hot, tbh) can utilise the PSU fan in a negative pressure config.. Then use positive pressure on the motherboard side. with an exhaust on the ram side in the edge (right now, you will re-circulate motherboard exhaust right back into the intake fan). 

 

You will avoid mixing different heat outputs and turbulence inside the case. 

 

I would say, the IO hub should at most contain power/reset button and 1 USB. And audio jacks, if you need them.    

[startrek03]

21 hours ago, illerin said:

Thanks Burh4n for your input! Will differently have to try the fan both ways and bench mark it once its built. There is a second exhaust under my graphics card, though it will be smaller since i'm going to make a second slot increase i go with a double slot card, but i get what you mean by the mobo just spinning the same air. Was thinking about putting a 60mm fan for a side exhaust by the mobo so the air is drawn across the case. Dont think this would detract from the look of the case and it wouldnt be blowing hot air on my legs. 

 

Made the power strip cable box as a test run for making the case and think it turned out nice. This doesnt have the 1/8" alum trim i intend to put on the case so it does look a little bare. Thinking about getting some self etching alum paint and testing out coloring the alum. 

The wooden part of th case looks really good. Well done!

[illerin]

8 hours ago, burh4n said:

Not a bad thought, but might add some noise, definitely look for some quiet fan options there. Also, that might be blowing directly onto your networking equipment right? Just thinking about thermals under the desk in general, and wondering if you'll have enough space between the wall and the edge of the desk for airflow? Your legs might get warm under the desk, especially depending on how tall you are (have you checked to see how much space there will be from the top of your legs to the PC case?).

Do you really need the reset button? Personally I'd ditch the reset button and keep only the power light and switch, then a USB cable would be fine. Additionally, you could use some CAT5 cable or even HVAC thermostat wire if you need extra conductors, but I get it if you have a spare USB cable already you don't need to buy cabling. 

The vent would be forward of the front of my router, i do have an air gap between it and the desk to help with venting. For the back vent the lip of the desk is smaller then shown in CAD and wouldn't block the back vent. Ended up using a 3/4" sub panel instead of a 1/2". Checked knee clearance with my first test box and good there. 
A cat5 cable would be perfect! Could just run all the pins for the varies lights and switches and use what i want, thanks for that idea! 

[illerin]

7 hours ago, PriitM said:

While its not a bad idea to separate individual fans to respective coolers, it is a bad idea to have the internal volume mix. Different sizes of fans, intake/exhaust port sizes, fans speeds and airflow patterns. Plus, a narrow case has a hard time of controlling radiant heat (since mirroring surfaces are so close to the source). All positive pressure would keep hotter air inside the case longer (relatively speaking), allowing radiant heat to build up in the case walls. 

 

I would add partition walls between the different heatzones and have respective exhaust ports for each one. 

 

Blower GPU will handle itself, HDDs (wont get that hot, tbh) can utilise the PSU fan in a negative pressure config.. Then use positive pressure on the motherboard side. with an exhaust on the ram side in the edge (right now, you will re-circulate motherboard exhaust right back into the intake fan). 

 

You will avoid mixing different heat outputs and turbulence inside the case. 

 

I would say, the IO hub should at most contain power/reset button and 1 USB. And audio jacks, if you need them.    

Could you expand upon why internal volume mixing is a bad idea? I would think making sure you have some internal air mixture would help reduce hotspots in areas that dont have direct airflow on them.

 

The psu and gpu are their own independent intake/exhausts, but like you mentioned they will still radiate heat into the general volume. This was the intent of the 120mm fan to push or pull air across the case. With burh4n idea of having the 120mm exhaust it would pull the air from the cpu intake across the case and out. The extra 60mm would also pull air across the RAM. The SSD's are just below the fan cause thats where they would fit. I could see moving the extra rectangular opening that doesnt have a fan to a more central locations that would either act as an exhaust or intake based on the systems internal pressure, thus creating more movement of air thru the case.

I would think that separating the 120mm fan side from the mobo side would create more corners that wouldnt get airflow then keeping it more open.

[illerin]

Updated model shots with the 120mm flipped, 60mm added and a cat5 connector for external input.

 

Or at this point would it be better to slide the 60mm down and switch to an intake blowing over the mobo's vrms? So the cpu fan and 60mm brings air in one side and the spare pcie slot and 120mm exhausts.

 

[PriitM]

Its counter intuitive: if you keep a relatively large volume, the summed up mass of air is big. Any kinetic energy you put into that volume of space, gets that much dissipated. For effective airflow and cycling of air, its better to keep volumes low. 

 

Keeping internal volumes low, you increase the chance that air will get to potential hot spots and circulating better. Have you calculated theoretically how fast the internal volume of air gets cycled? Based on manufacturer rated flow rates etc. 

 

Pic 1: you can see how much the air must travel in order to reach the exhaust. Plus marked potential hot spots in red.

Pic 2: Sectioned off design. Added intake 60mm to blow over the board next to the rear I/O. This way, even if you dont move much air on idle over the mobo components, you will still have some forced air pushing over and into corners. 

GPU will take care of itself and could also pull enough airflow to keep SSD area decently cool. Or keep the 120mm fan, but flip it to intake. GPU will get fresh air as intended, will help in exhausting some of the pushed in air. And wont have to work as hard to cycle that volume of air. 

[illerin]

9 hours ago, PriitM said:

snip

 

 

Yeah once i looked at the plan view i figured i needed to move the 60mm fan down. I'll throw the mid barrier wall in, gives me another place to secure the gpu to as well. 

 

As for air turnover its about 3x that of a mid tower case(41L) with 3 120mm intakes, assuming the 120mm, 92mm and 60mm fans are intakes, ignoring the GPU and power supply fans. The internal volume is 8L without any parts loaded.

[illerin]

Made a test piece for the side wall with vents to see how well the hole pattern would turn out, got better with them as i went along. 

[burh4n]

@illerin those corners look beautiful, nice work! Wondering if you're willing to share a STEP file of your CAD design (or native file if you're using Solidworks)? If I have some extra time, I'm curious to run it thru a computation fluid dynamics (CFD) simulation to help give a better idea of what you should expect.

 

I definitely agree with @PriitM that adding a partition should help reduce the mass of air that each fan would have to handle, but I still think that active exhaust would be more beneficial than passive (but happy to be proven wrong). 

[illerin]

@burh4n Always happy to find ways to improve the design, appreciate your guys help. Only have standard solidworks so dont have the simulation plugin for it. I've linked the soldiworks files along with a .step file as well. 

 

https://www.dropbox.com/sh/sks99m7071wos2b/AABasQOoCgI8WMppd-cs9EE3a?dl=0

[PriitM]

That thing looks really nice. Always been a bit skeptical about kerf, since you gotta have a table saw with guides to work it. 

 

Interested on how the airflow performance would be on the CPU side, a real "case study" I would say 

 

[illerin]

@PriitM This is my first project with kerfs so I'm running test pieces to make sure i have it down, having fun with it though. That side test the radius came in at 1-3/8" instead of the 1-1/2" planned. This reduced the cases width by 1/4", so i'm going to have to dial this in and when i make the final sides do both at once so they come out equal. The length of the case will be easy to dial in as i just cut the front and back panel to size. 

Once i build the case i will probably run tests with the fans in different configurations just to see how different of a result i get. Glad to hear that no one thinks this is just a fire waiting to happen. 

[PriitM]

I have been using my 3rd gen plywood case for 5 years now. First 2 summed a total of 2 years. 7 years of using a wood case, never had a problem.

 

Keep it well grounded tho. And most important: dont skimp on the power supply. I have a 550W passive platinum grade PSU to power a hungry 7700k (started with i5-6500) and a R9-390X for 5 years. Not a single problem. 

 

How the 3rd gen works and looks? Will post specs, cad drawings and test results once the 4th gen is finished (probably when Big Navi proves to be a well sorted out)

[TVwazhere]

On 8/29/2020 at 4:53 PM, illerin said:

Made a test piece for the side wall with vents to see how well the hole pattern would turn out, got better with them as i went along. 

Spoiler

 

 

Just wow. 

[illerin]

Getting my remote hub figured out while i wait for the aluminum panels to arrive. =D Remembering why i hate soldering!

[startrek03]

On 9/10/2020 at 11:51 PM, illerin said:

Getting my remote hub figured out while i wait for the aluminum panels to arrive. =D Remembering why i hate soldering!

Looks good! The SD slot could be cleaner, but from a distance you probably won't even notice it and I also know that it's not that easy to make such a slot.

[illerin]

@startrek03 Yeah, not too happy with the sd slot, thinking about having another go at it to get that slot better. Thinking i will do a small plunge cut to get two vertical lines to make the slot cleaner. 

 

 

Got the alum sheets in and did a test fit with my test side panel to make sure the slot fit correctly.(it did =D ) 
I plan to stain the wood side panel, and paint the wood subpanel thats below the perforated alum black so it matches the foam filter(not shown). Going to either brush finish the alum so it all looks the same, or just paint all the aluminum parts.