Spartan: The 16.7L, full ATX tower case

D_McG

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Dec 17, 2016
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Hello World! (tis my first post)

I've been a long time lurker on this forum, and in no small part have learned a lot from @Aibohphobia on the STX160 thread.

While I’ve enjoyed building an ITX system in an NCASE M1 (first edition), the motherboards that suit my needs are offered only in the full ATX (12” x 9.6”) form factor. ASUS latest ROG boards often are in EATX (12” x 10.7”) form factor.

Tired of not finding what I want in a case, I thought I’d develop my own. So I give to you, the Spartan.



The frame will be made out of 18 gauge (0.050”) brushed stainless steel (no powder coat). All internal bend radii are also 0.050” (making the math easy). I’ll consult Protocase on achievable bend radii and adjust it in the final CAD model if needed.

The dimensions of the frame are 15” x 12” x 5.5” (381mm x 304.8mm x 139.7mm). The side panel is currently planned to be 0.118” (3mm) acrylic. I’m considering using thicker stainless steel for the top and bottom panels to allow for countersunk screws. For the moment, keeping with 18 gauge stainless steel yields outside dimensions of 15.1” x 12” x 5.618” (383.5mm x 304.8mm x 142.7mm) which comes to 16.7 liters. This excludes feet, card flange, fan grills, and screw heads.

This case can be equipped with:

1 - EATX motherboard up to 12” x 10.7”
7 - PCIe cards including 2 GTX 1080’s in SLI (reference design with blower)
3 - 120mm intake fans
2 - 80mm exhaust fans
1 - 140mm exhaust fan under a Noctua NH-C14S (115mm in height) blowing out the side
or... 2 - 92mm fans on a Noctua NH-D9L blowing out the back.
2 - 2.5” HDDs (15mm in height)
1 - SFX-L power supply (SX700-LPT recommended)



The design is primarily a U-shaped enclosure with flanges on all sides. I’ve replicated the closed corner design to all eight corners; so that it’s symmetrical from the front, and provides even support on the bottom when standing vertically.



Symmetry is important to me here. Rather than bending flanges from the top and bottom panels to support the acrylic side panel, I’ve added L-shaped brackets that bolt to the top and bottom. The reveal is then identical between left and right sides. This also allows me to choose a different material for the top and bottom if desired.



I’m trying to keep the price down by not requiring extraneous panels. The motherboard panel is solid and forms the left exterior side. The blind through hole standoffs will be visible on that side (simple hexagon), but I’m ok with that.

I’m keeping the price down by also reducing the number of cutouts per fan to a single round circle; at least for the prototype. I modeled several hexagon grilles, varying from roughly 50 to 100 cutouts per fan, but after watching video of how long it takes the laser cutter to start a new hole, it became impractical.

I found the following website to be helpful in my decision to go without an integrated grill, with perhaps wire grills bolted on (more on this later).
https://www.pugetsystems.com/labs/articles/Effects-of-Grill-Patterns-on-Fan-Performance-Noise-107/

Screw holes:

7 - PCIe slot retention holes (2.5mm diameter) tapped with M3 x 0.5mm thread
9 - BSO4-632-12 Blind Threaded Standoffs for Stainless Steel 6-32 thread .375”
40 - SP-M3-1 Self-Clinching Nut For Stainless Steel M3 x 0.5mm thread (12 on top, 12 on bottom, 12 on acrylic side, 4 for feet)

The top and bottom panels will attach with M3 x 4mm Button Head Socket Cap Screws https://www.amazon.com/dp/B01CKU0UP2/?tag=theminutiae-20



Sheet metal bending should be similar to the SFX160 project. Only 3 press brake finger changes should be needed, and 3 back gauge changes.



Bend 1 is still the PCIe retention flange, albeit 5.55” long for 7 slots. No PEMs here, I'll have them tap the holes. This also helps them passivate the stainless steel after all bends are made before installing any PEMs.

Bends 2 and 3 are identical on Spartan. The two L-brackets are the same bends as the center of bends 2 and 3, so no additional setup needed.

Bends 4, 5, 6, and 7 are all the same width and can use the same fingers.



The flanges are tapered at the ends so that bends 4, 5, 6, and 7 may be bent past 90 degrees by up to 5.7 degrees when dealing with spring back. All corners are rounded to prevent injury.

There is 0.553” (14mm) of clearance between the top of a video card (assuming it doesn’t violate the PCIe spec) and the inside of the acrylic window. This requires the use of low profile 90 degree power cables, such as these http://kareonkables.com/products/90-degree-female-8-pin-to-8-pin-pci-e-video-card-adapter-version-1 which are only 0.4375” (11.11mm) in height.

High-Bandwidth SLI bridges that are embellished with LEDs seem to be oversized. There doesn’t appear to be enough room under the flange to install them; however, ASUS has made a narrow and thin HB SLI bridge that appears to fit; even if it needs to go under the flange https://www.asus.com/Motherboard-Accessory/SLI-HB-BRIDGE2-WAY-M/

There is room for two 2.5” HDDs on the bottom of the case. While I’m not sure I’ll be using them personally (as I’ll be going for a Samsung 960 Pro 1TB M.2 stick on the motherboard) I’ll add rubber grommet mounts on the bottom of the case for them. Power for them is right there (able to run a short single wire from the PSU to each HDD). SATA cables with 9.6” ATX boards are straight forward; however, use of 10.7” EATX boards may preclude access to the SATA ports unless a slim 120mm fan is used, or the ports are straight up rather than right-angled.

To try and dress-up the front of the case, I came across the following 360mm radiator fan grill and thought it looked great on the Spartan.

https://mnpctech.com/pc-computer-al...ill-360-open-ring-fan-and-radiator-grill.html



Here's an orthogonal view of the inside. Note: the older NH-C14 is pictured; not the NH-C14S that is offset towards the power supply to help with a GPU in the first slot.



The motherboard layout here is from the Gigabyte GA-Z170X-Designare. I wanted to play around with Hackintosh. Slot 1 will have a wireless card. Slots 2 and 5 will have reference blower Geforce GTX 1080 cards (once NVIDIA releases a Mac driver for Pascal). Slot 7 will have a PCIe x4 Gigabyte GC-ALPINE RIDGE card; adding two additional Thunderbolt 3 / USB-C ports for a total of four, three of which have DisplayPort pass thru for 4K retina displays. On this motherboard, when both the PCIe x4 M.2 and PCIe x4 Slot 7 are used, all of the right-angled SATA ports are disabled; however, 2 vertical SATA ports remain for the two HDD mounts.

I'm still working on where to place the power button and front USB 3.0 ports. They might go on the top panel, though the fan or GPU may interfere, or maybe they can be angled out, or even just attached to the acrylic and come out the side.

All comments welcome!
 
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D_McG

Trash Compacter
Original poster
Dec 17, 2016
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Looking good! Quite polished so far. What about ventilation for the top GPUs?
There is a 120mm intake fan directly in front of the GPUs. The GPUs are intended to exhaust out the back with reference design blowers; not into the case.

I'm also considering (at least on my personal model) removing the metal in front of the double-wide slot brackets that block a third of the ventilation holes on the GPUs. I of course cannot presume which slots people want to use, but since it's brushed stainless steel, there's no finish to ruin. Just cut the dividers you want and file flat.
 

IntoxicatedPuma

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Feb 26, 2016
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not under 16L? No Buy. When will people learn that over 16L is just too big??

just joking. This is awesome. I love the Jonsbo RM2 case but don't like the lack of cooling - this seems to fix that and trim some of the excess space!
 
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Phuncz

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Welcome to the forum ! A very nice concept too ! Personally I would choose a CPU cooler that would fit with the fins parallel to the airflow, so you can ditch the fan and possibly use a beefier cooler, while utilizing the airflow that's already there from the casefans. I'm looking very much forward to the end-result, seemingly not far away with the design already being optimized for production, well done !
 

iFreilicht

FlexATX Authority
Feb 28, 2015
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Looks pretty darn great. Not everyone will like the limitation of reference height, but I think in this case it makes perfect sense. If you want a 16L ATX case, you have to cut corners, and I like that this case embraces that fact rather than trying to hide it.
 

D_McG

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Dec 17, 2016
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Personally I would choose a CPU cooler that would fit with the fins parallel to the airflow, so you can ditch the fan and possibly use a beefier cooler, while utilizing the airflow that's already there from the casefans.

The first 3U compatible heatsink that came to mind is the Noctua NH-D9L (110mm tall) pictured below. Max height for this case seems to be 120mm.

 

Thehack

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Mar 6, 2016
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Looks great. What about the consideration of adding vents for the bottom GPU (or top if you intend the orientation to be inverted)?

You can also choose to have just one panel be smoked acrylic to show off the innards.
 

D_McG

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Dec 17, 2016
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What about the consideration of adding vents for the bottom GPU (or top if you intend the orientation to be inverted)?
The case is indeed inverted; though it wasn't initially. I flipped it to conceal the cutout for the PSU intake fan, and it then made more sense once I needed to add eight cutouts for grommets to attach the HDDs. Additional intake vents would have to go into the top of the case, but the GPU(s) are already being fed by a 120mm fan in the front. Not sure (yet) that they need more air.

Anyone know how much air the reference GTX 1080 blowers move out the back per minute?

You can also choose to have just one panel be smoked acrylic to show off the innards.
The open side is indeed slated to be acrylic. Protocase doesn't stock smoked acrylic, only clear, but if I end up adding vents in the acrylic for the NH-C14S exhaust, I'm debating between CNC machined edges vs. laser cut; the latter needing a different shop.

If this ever goes into production, perhaps there will be a few options: clear acrylic with vents, clear acrylic without vents, maybe no panel at all for those that want tinted or colored acrylic from a different vendor. Will probably poll once I get that far.

The dimensions for the panel are 14.8" x 11.8" (375.9mm x 299.7mm) which sits just inside the outer bend radii.
 
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Phuncz

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The first 3U compatible heatsink that came to mind is the Noctua NH-D9L (110mm tall) pictured below. Max height for this case seems to be 120mm.

Hmm the D9L is about half the mass. After looking it up, it's not easy to find a heatsink under 120mm with having close as much mass as the C14S. I had heatsinks in my head that were wider than they were taller, but these aren't as good performers as the Noctuas And in the end, if your airflow is good, the mass be an important factor in keeping temperature and thus noise under control.

So if possible, I'd try to turn the C14S 90° clockwise or anti-clockwise and see if it can fit. The thing I'm worried about with your original orientation is that the fan will be having a hard time because of the limited space between the heatsink and top panel. Maybe I'm just totally wrong on this part.
 
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Sean Crees

Airflow Optimizer
Jan 1, 2017
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You're not going to be able to fit those graphics cards in that case without a minimum of 6" of width. Just from the edge of the pci-e bracket tabs to the top of the graphics card is 5 inches, you're going to need another inch for the power connectors + width of external panels. Unless your planning on doing some sort of bulge on the side panel or let the power cables for the graphics cards stick outside the side panel. Just looking at the model its clear the tabs from the pci-e brackets are sticking out the side of the case.
 

D_McG

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Dec 17, 2016
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The thing I'm worried about with your original orientation is that the fan will be having a hard time because of the limited space between the heatsink and top panel.
I didn't draw it yet, but I envisioned vents cut into the acrylic side panel to allow the NH-C14S to exhaust straight out. The 80mm rear fans are to help keep everything else cool; like M.2 and VRM.
 
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D_McG

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Dec 17, 2016
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You're not going to be able to fit those graphics cards in that case without a minimum of 6" of width. Just from the edge of the pci-e bracket tabs to the top of the graphics card is 5 inches, you're going to need another inch for the power connectors + width of external panels.
As I wrote in the opening post, there is .550" between the top of a GPU and the inside of the acrylic side window; which bolts on from outside the frame. The 90-degree adapter from http://kareonkables.com/products/90-degree-female-8-pin-to-8-pin-pci-e-video-card-adapter-version-1 requires .4375" of space, so not a problem.
 
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Aibohphobia

aka James
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Feb 22, 2015
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Looks really good! I'm impressed with the attention to manufacturability. Did you have any prior experience with sheet metal design?

And it looks like you're using SketchUp, if you want, you can send me the .SKP and I can convert it to .STEP for Protocase.

9 - BSO4-632-12 Blind Threaded Standoffs for Stainless Steel 6-32 thread .375”

You may consider the BSO4-8632-12, it's a larger diameter version so there's more surface area for the motherboard to rest on.

The flanges are tapered at the ends so that bends 4, 5, 6, and 7 may be bent past 90 degrees by up to 5.7 degrees when dealing with spring back.

I wouldn't get to hung up on that, the manufacturer will correct the taper angle as necessary to account for the material and tooling based on their internal data.

All corners are rounded to prevent injury.

Yay!

This requires the use of low profile 90 degree power cables

The wires on the SilverStone SFF power supplies can bend sharp enough to fit within 14mm. Though they may be pressing against the panel.

I'm considering changing the tapped threads on the card retention flange from 6-32 to M3

Yesss, join the dark logical side.

And if you're going to do that, you might as well change the motherboard standoffs to M3 as well. The fewer different types of screws you need the better, so having all #6-32 or all M3 makes more sense.
 

iFreilicht

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Feb 28, 2015
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I'm considering changing the tapped threads on the card retention flange from 6-32 to M3; so that in 18 gauge SS, the number of threads in contact would increase from 1.6 to 2.5 and allow reuse of the same M3 x 4mm Button Head Socket Cap Screws

Seems like a no-brainer to me.
 

D_McG

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Dec 17, 2016
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Looks really good! I'm impressed with the attention to manufacturability. Did you have any prior experience with sheet metal design?
Thank you!

I was a technical drafter for 5 years (3 at a tech school and 2 at an engineering firm), and was an ME major for 3 semesters before switching to CS. I used Autocad r14 at work for both mechanical and architectural drawings. I drew several 2D sheet metal flat patterns including duct work for plenums and adapters from square to round, and other misc brackets.

It helped going to a tech school where I took metal fabrication and machine shop as exploratory classes; getting experience with a box and pan brake, spot and oxyacetylene welding, metal lathe, etc.

And it looks like you're using SketchUp, if you want, you can send me the .SKP and I can convert it to .STEP for Protocase.
Interesting offer! I'll keep it in mind. The modeled closed corners are actually separate components in my SketchUp file; as it helped keep the bends orthogonal through several iterations. The corners would need to be corrected in a real sheet-metal-aware CAD program. The model is water tight without the closed corner components; but looks like it has an open corner relief.

I'm considering getting a trial of Solidworks and/or SpaceClaim for this project; hopefully I can draft it up and get a turnaround with Protocase inside 30 days. I want to properly model that 360mm fan ring (a bit smaller) and get a quote for CNC machining it as well. I also need to either find 1.25" diameter feet that accept an M3 screw from the bottom, or model one and have them made too.

You may consider the BSO4-8632-12, it's a larger diameter version so there's more surface area for the motherboard to rest on.
Thank you for bringing this to my attention. I did not know that there were wider PEMs. While I now want to use these, they are neither stocked nor listed by Protocase. I don't know what their min quantity to order would be. While I can buy 9 of them for $4 USD from swaco.com, I don't think Protocase would appreciate working like that.

might as well change the motherboard standoffs to M3 as well.
It turns out the wider 6-32 standoff is .280" (7.112mm) while the wider BSO4-3.5M3-10 is only 5.39mm. I'd have to go up to an M4 thread to get back to 7.12mm; which defeats the purpose and won't reduce the unique screw count. SFX power supplies still require 6-32 threads, so I'd like to keep the motherboard standoffs as 6-32 threads. The height would also change from .375" (~9.5mm) to 10mm for what it's worth.
 
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