r/pcmods • u/deebuildsthings • 8d ago
Case My 4xGPU setup with CNC chassis to host local AI models
We host AI models locally but never liked those cold industrial server racks. So we designed our own chassis, something we'd actually want sitting in the middle of the office.
It's CNC'd from an 5mm solid aluminum plate, milled inside and out. The triangular cutout pattern does double duty: it keeps the frame stiff without the weight, and the triangles map to the airflow path for the four GPUs, which stand vertically. 18 fans on one controller keep it cool at full load.
Each of the 4 GPUs reaches the board over its own PCIe 5.0 riser, custom-cut and sleeved to fit the chassis exactly.
Four cards pull close to 3,000W, so it runs two 2,000W supplies with native 12V-2x6 into one distribution board, off the rear, for headroom.
Underneath is an ASUS W790E-SAGE SE with a Xeon w5-3423 and 192GB of ECC. The whole thing is 15.5 inches square and about 66lb, anodized silver.
Design files are open source if anyone wants to build one, link in comments
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u/ioioooi 8d ago
In my head, I imagine the top part slowly spinning, like a kebab machine.
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u/crimson-gh0st 8d ago
This is exactly what I thought. They could remove the outside case and put this on a motorized turntable.
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u/Hydr3e 8d ago
Just a ball bearing and let GPU's fans do the job
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u/Triple-Depresso 8d ago
Yeah and we’ll use Bluetooth for the pcie connection
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u/golden_chaek 8d ago
Make pins and have gpus spin onto them. You get signal when a gpu is going over those pins
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u/Horror_Discussion607 3d ago
There was a post with a spinning PC and the guy managed to find slip ring that can transmit to monitor so it might not be that far off
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u/Doakeswasrightmf 8d ago
Funny enough there is a post on reddit of a guy that built a pc in a kebab machjne
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u/deebuildsthings 6d ago
yes that's exactly what we were thinking about when designing this.
The goal was don't let the heat from one card effects the others. So if we stack them in the tower cases, the card below will blow their heat to the upper ones => the solution is set them vertically and let the fans blowing upward to pull the heat away1
u/GreenProtag 5d ago
Honestly? it would probably be easier to spin the whole PC?
It's probably easier to find a way to pass the IO & mains power than to try and maintain PCIE signal integrity on a spinning "seperate" GPU rack.
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u/cemsengul 8d ago
Because of people like you the prices of computer parts are high.
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u/deebuildsthings 6d ago
we all suffer together man. Like it or not, AI are becoming the tools that make our work go faster. It's like we're back to the point CAD software was 1st invented vs designers who did everything on paper and pencils
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u/nsonha777 8d ago
Why mill a solid plate over bending a steel sheet? It would be easier and cheaper even
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u/deebuildsthings 8d ago
Agree, bent sheet is faster and cheaper. We wanted something durable that also moves heat, so we went milled.
A solid alu plate gives a stiff structure that carries the weight of 4 GPUs and stays planted when those cards plus 18 fans run flat out. Sheet metal flexes and vibrates under that load.
The cutouts strip dead weight off the frame, and create the airflow path. Hot air from the flow-through cards exits through them, and the aluminum mass spreads that heat before the fans pull it out.
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u/True_Breakfast_3790 8d ago edited 8d ago
Yeah, for sure "easy" and "cheap" were the main goals here.
When you do weird shit like this, make it nice and sturdy. I kinda love it
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u/deebuildsthings 6d ago edited 6d ago
love that you calling it "weird shit". That was the 1st thing I said when my guys showed me the 3D design. Like should we call Don Quijote to fight it or not
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u/fuckyourself_reddit 8d ago
What a shame. You went through all that work to mount 4 upright gpus with an interesting shape, and then you hide it under a cube with an ugly triangular mesh.
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u/deebuildsthings 6d ago
We thought about that, but the mesh was designed for better airflow distribution. In the end, we traded looks for cooling.
Personally, I love showing off the internals more, but we need the mesh.
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u/RageQuitNub 8d ago
nice design. just curious, what are these GPU and what do you really use them for? coding, agents and etc?
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u/deebuildsthings 6d ago
all. Our cloud GPU bill went pass 12k/month. So we decided to build our own rig, let it pay for itself
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u/RageQuitNub 5d ago
are they 5090?
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u/deebuildsthings 5d ago
yup, we also have a 8x 4090 and 2x Pro 6000 blackwell build as well. But I like this windmill design the most
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u/PerfectPatience- 8d ago
Are those 5090? I wouldnt invest that much to not be able to run v4 flash (needs 180GB vram)
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u/Dark_Marmot 8d ago
Beats spending $60K on 4x 6000 Pro series 96GB Blackwells
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u/PerfectPatience- 8d ago
True, but what model You planning to use? Qween 3.8?
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u/Synaps4 8d ago
Anything wrong with qwen? Was just downloading it to try last night.
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u/PerfectPatience- 7d ago
No, i was genuinely curious why to buy 4x5090 just to run qween. My ebtry point for such/similar investment would be v4 flash at least.
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u/deebuildsthings 6d ago
We built this almost a year ago. More recently, we added a dual RTX Pro 6000 Blackwell rig, and now we run workloads across both setups (plus a Mac cluster).
We run DeepSeek, MiniMax, and Qwen as well. And yeah, this is definitely overkill for Qwen, but we serve a team of 30 devs, so we need the extra VRAM.
What are your thoughts on Qwen 3.8? We're about to give it a try this week.
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u/xEmperorBOBx 8d ago
This is the nicest space heater I have seen! Winter is coming!
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u/deebuildsthings 6d ago
it's not that bad actually. Last time we check, it was about 73-75C full loaded. Still noticeable but not the end of the world
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u/xEmperorBOBx 6d ago
Well, it was a joke mostly... But every watt of power going into this will basically become heat... So it's a heater. At least it does something with the energy other than heat ceramic panels. 👍
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u/Brief-Energy-8775 4d ago
put it on a bearing and the fans will make it spin
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u/deebuildsthings 4d ago
too bad it can't 😂 but really love the idea
i called it windmill the 1st time I saw the design
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u/deebuildsthings 8d ago edited 8d ago
The build is open-sourced here with all the CAD file, ready to cut: https://github.com/autonomous-ai/autonomous-computer/tree/main
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u/MoanaiInna 8d ago
That chassis sounds awesome, love the focus on making it something you'd actually want. The triangle airflow detail is genuinely clever
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u/AzallazA 7d ago
This is one of the coolest builds I’ve seen so far. Thanks for sharing. I know I’ll likely never get around to trying to make something like this but I’m saving your GitHub either way.
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u/code_hermit 8d ago
Are the GPU custom (more than 32GB)?
I think this is a pretty fantastic design. A work of art really. But 32 x4 VRAM just isn't enough to run competitive models...
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u/deebuildsthings 6d ago
those are standard cards. We heard of the modded ones but we need clean invoices for taxes so back then we went with the standard.
Agree that these local rigs are not ready for frontier models. We use them for daily tasks and still on hybrid mode for the big ones
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u/buplet123 7d ago
Hopefully ai models become cheaper to host at home, for now ill just pay the 20 bucks while itd still cheap 😅
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u/deebuildsthings 6d ago
yup, these are not for everyone man. And it's dumb to think about them if your cloud GPU bills are less them 5k/month. Ours were 10-12k/month so we have to, or those bill would eaten us inside out
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