3D-Printed Cooling Mod Tackles NVIDIA Jetson Thor Edge AI Thermal Throttling

A fully parametric, modular external cooling dock and aerodynamic shroud for the NVIDIA Jetson AGX Thor Developer Kit (Tegra264 Blackwell architecture).

Designed to eliminate thermal throttling during sustained high-concurrency LLM inference and training (vLLM, Qwen 2.5 / 3.8, speculative N-gram offloading) without datacenter noise or invasive hardware modifications.

The NVIDIA Jetson AGX Thor Developer Kit is an edge AI powerhouse, but its chassis features an asymmetric thermal architecture:

1. Active Lower Half : The bottom section houses the Tegra264 SoC, cooled by an internal high-RPM radial blower.
2. Passive Upper Half (The Heat Trap) : The top compartment houses the high-power28V DC input switching VRMs (hwmon5 pulling ~76W–80W+), four 10GbE/MGBE controllers, the QSFP28 100GbE cage, and the PCIe Gen5 M.2 NVMe slot.There is no internal fan in the upper half of the chassis.
3. Convective Pooling : Heat naturally rises and becomes trapped under the solid top aluminum casing. Under heavy workloads, Crucial Gen5 NVMe drives heat-soak past50°C at idle and exceed60°C–70°C (124°F+ heatsink surface temp) during continuous speculative decoding and data offloading, triggering aggressive drive throttling and carrier board thermal warnings.

This system splits cooling into two independent, aerodynamically targeted zones using standard 120mm fans (such as the ultra-quiet Noctua NF-A12x25 5V PWM):

                       [ Upper Noctua 120mm Fan ]
                                  │
                                  ▼
                     ┌────────────────────────┐
                     │ 70mm Tall Cooler Box   │ ──► 20mm Roof Air-Knife Deflector
                     │ (24.5° Downward Ramp)  │     (Sweeps across top chassis)
                     └───────────┬────────────┘
                                 │
                                 ▼
                     Direct Airflow under NVMe Heatsink

┌─────────────────┐                                  ┌──────────────────┐
  │ Blanking Cover  │ ◄── [ Internal Fin Matrix ] ◄──  │ Lower Fan Dock   │
  │ (Pressure Seal) │                                  │ (Noctua 120mm)   │
  └─────────────────┘                                  └──────────────────┘

1. Lower Fan Dock (thor_base_fan_box.stl) :

• A 30.0mm height base dock that seats a 120mm fan in a recessed pocket with a 5.0mm perimeter air-trap shelf.
• Features a $23.6 \times 109.6\text{ mm}$ spigot with$5.0\text{ mm}$ protrusion and a$0.8\text{ mm}$ lead-in chamfer that locks snugly into Thor's lower underbelly opening.
• Converts the underbelly cavity into a pressurized plenum, forcing laminar air through the internal heatsink fins.

2. Blanking End-Cover Plug (thor_end_cover.stl) :

• A solid 10.0mm deep block with matching $5.0\text{ mm}$ spigot that plugs into Thor's opposite opening.
• Prevents air from escaping out the back side, ensuring 100% of the positive pressure is forced through the heatsink matrix.
• Acts as a level, non-wobbly structural foot for the left side of the developer kit.

3. A solid 10.0mm deep block with matching

Upper Tall NVMe Cooler (thor_tall_nvme_cooler.stl) : - An independent 70.0mm tall box (10.0mm taller than the 60.0mm Thor chassis) dedicated to the top half of the unit.

$24.5^\circ$ Aerodynamic Ramp$Z=55\text{mm}$ ) and slopes continuously downward to$Z=4.8\text{mm}$ at the spigot face, eliminating dead volume and guiding high-velocity air directly under the NVMe heatsink.

Underbelly Cavity : Underside of the ramp is hollowed out to save material and print time while retaining full perimeter contact walls down to the desk for rock-solid stability.

20mm Roof Air-Knife Deflector : Extends$20\text{ mm}$ forward over Thor's roof with a downward slope ($Z=63.4\text{mm} \rightarrow Z=62.0\text{mm}$ ), leaving a precise$2.0\text{ mm}$ clearance that blasts a high-speed air knife across Thor's top plate, continuously purging rising heat from the 28V VRMs.

The following benchmark data was collected on hardware (amano) under a sustained 97% vLLM load running Qwen 2.5 / 3.8 Next with speculative N-gram NVMe offloading at 76W–80W continuous input power:

(Note: Under idle and light workloads with the full dual-fan system, GPU core stabilizes at 36.9°C and NVMe temperature stabilizes at 32.0°C.)

All parts are engineered in OpenSCAD with strict consideration for FDM printability, layer orientation, and overhang geometry.

• Slice the fan boxes in the print_spigot_up orientation (resting flat on the rear$-X$ wall).

Massive Bed Contact Area : Provides an$8,800\text{ mm}^2$ flat base on the print bed with zero warping risk.

100% Self-Supporting Ramp : When placed on its back wall, the internal$24.5^\circ$ downward ramp tilts to$65.5^\circ$ from the horizontal bed$45^\circ$ overhang threshold. It prints withzero support material required inside the chamber !

Minimal Tree Supports : Only a single slicer tree support trunk is needed underneath the horizontal fan shelf overhang inside the pocket.

The master design file thor_cooler.scad is 100% parametric and fully compatible with the OpenSCAD Customizer:

// Select component to render:
selected_component = "tall_cooler"; // ["fan_box", "end_cover", "tall_cooler", "both_assembled"]
// Choose orientation:
view_orientation = "print_spigot_up"; // ["working", "print_spigot_up"]

To compile individual STLs via CLI:

# Render Lower Base Dock
openscad -o stl/thor_base_fan_box.stl -D 'selected_component="fan_box"' -D 'view_orientation="print_spigot_up"' thor_cooler.scad
# Render Blanking End Cover
openscad -o stl/thor_end_cover.stl -D 'selected_component="end_cover"' thor_cooler.scad
# Render Upper Tall NVMe Cooler
openscad -o stl/thor_tall_nvme_cooler.stl -D 'selected_component="tall_cooler"' -D 'view_orientation="print_spigot_up"' thor_cooler.scad

This project is licensed under the MIT License. Feel free to modify, print, and share!