Minimalist BC-250 Case

Introduction

The Minimalist is a simple to print and super compact case for the BC-250 board.

It took a lot of iterations to come to the current design : compact (5L), cheap and easy to build, no compromise on performance, active backplate cooling, as quiet as possible considering it keeps the original heatsink, easy to install.

The newest revision of the case takes into consideration the recent findings about heatpipes orientation, and allows upward configuration (PSU and connectors up). You can still choose to keep the PSU down if your board happens to behave the same with connectors either upward or downward.

Specifications :

(*) that's the frequencies the system is able to keep at the end of the Superposition benchmark, please note it entirely depends on silicon you have, fan models you choose, the quality of the thermal contact between the APU and the heatsink, and how high you choose to clock your CPU.

(**) the case is designed to throw a substatial amount of air to the PSU via its 2 lateral fans and vents; you can safely remove the top cover and 40mm fan from the PSU to expose PSU's components to this airflow.

Updates

25-oct-2026: new revision of the case, named Reverso, that can be used flipped-over (i.e. with the PSU and connectors upward in order to improve heatpipes position). This new revision is to be considered a fully-functional prototype, it works great, but some minor details might still evolve (like SSD slot location). The HP PSU option is still pending testing, your feedback is welcome.

18-oct-2026: added a prototype version for HP server PSU. I don't own any yet, but found a good model online, please test the rear part first and come-back to me if you have any concern ;-) All the missing parts to be taken from the V4 folder (brackets, handle and grills)

28-sept-2026: trimmed the guide rails a bit so they don't come in contact with the heatsink (which was not the general case, except for one unlucky guy so here we go)

07-sept-2026: new version of the case :

• Side grills are not screwed anymore, they slide into dedicated grooves

• 2 side panels are offered to choose from, but you can easily design your own

• Improved the mouting process by removing a guide and adding some mounting tabs on the front panel

• Feet design hase been reviewed and hopefuly improved :-)

16-aug-2026: transitioning documentation to the latest version only (V3). I'll leave previous versions STLs if anyone needs to reprint a part, but I won't maintain those anymore.

25-jul-2026: new version for the 240 model with significant improvements :

• bottom hatch to improve installation and maintenance

• APU fan is now centered so you don't have to strip side fins (only center ones)

• grill-less design to reduce intake air noise, choose yours

10-feb-2026: PSU mounting is more open, to allow for other brands, such as Fortron or Apevia. Also, there's a new revision of Model 200, which now share the same back and handle parts as Model 240. You can print both fronts and have a try !

07-feb-2026: active [back-plate & PSU] cooling & improved airflow for Model 240

Parts List

• Power Supply :

  • Flex ATX PSU (e.g. Metalfish 300W or FSP 500-30AS)

  • *NEW* HP server PSU (HSTNS-PL28, HSTNS-PL29, HSTNS-PD29)

• Power-Button : 21mm ATX power button (https://www.amazon.fr/dp/B07VBV518H)

• Cooling : 

  • APU fan : 120 x 25mm high-static pressure (e.g. ARCTIC P12 Pro PST CO)

  • Backplate fan : 120 x 15mm (e.g.: Thermalright TL-C12015 or ARCTIC P12 Slim PWM PST)

• Front USB port (optional) :

  • 24mm round port (https://www.amazon.fr/dp/B0DYNFZWD4)

  • 50cm USB3 cable

  • 180° USB3 down-adapter (https://www.amazon.fr/dp/B0BNKFSQHZ)

• 120mm steel fan grills (optional) (https://www.amazon.fr/dp/B0CZLPJXFD)

Printing Guidelines (0.4mm noozle)

• Filament :

  • my prototypes were printed using PETG-GF and PETG-CF. I didn't get any satisfying results with PLA, but your mileage may vary...

  • ~600g filament for the case

  • ~20g filament for the handle

  • ~40g per grill

• My slicing parameters :

  • Precise wall

  • Only 1 wall on first layer and top surface

  • Walls loops : 3

  • Detect thin walls

  • Top and bottom shell thickness : 0.7

  • Infill-Pattern : Gyroid, 15% density

  • No support, no brim (feel free to use glue)

  • Adaptative Layer Height

• Printing time with PETG-CF on a Centauri Carbon : ~8h back + ~7h front

Mounting Guidelines

Mouting this case is pretty straightfoward, and has been greatly improved with the latest versions.

• Use 5mm tapered fan screws everywhere, except two 3.5mm PC screws for the brackets
  

  

• M3 brass inserts can be used on 5mm holes. They are not specifically recommended, except maybe for the handle (2 holes on top of the case).

• Apply force carefully, PETG isn't very strong and will tear appart if tightened too hard

Mounting the Rear Part

1. Remove steel brackets from the board

2. V3 : Install the 3 printed brackets, with the triangle-sign facing to the board (see pictures) :

   • the long bracket at the front, upper hole, facing upward

   • the 2 short ones at the rear & backside, facing rearward

3. V4 : Install 2 short brackets (long one IS NOT needed anymore),  at the rear & backside, facing rearward

4. Install and screw the PSU first

   • Note: you can safely remove the PSU's top cover, as it receives substantial airflow from the side-fan. And if you are confortable with it, also remove the PSU's 40mm fan, you system will be much quiter under load.

5. Slide-in the BC-250 board

   • Make sure IO ports are perfectly aligned

   • Secure the board using 2 x 5mm tapered screws near the IO ports to the printed brackets

6. Install the fans using two screws (keep them loose, don't tighten yet), then connect the fan(s) to the board

7. Route the optional USB cable from the back to the front

Mounting the Front Part

1. Install the ATX switch. You'll need to remove the connectors first; mark their positions before removal (e.g. 1-M-0). The connectors do come out after some gentle left-right rocking. Reconnect the switch after installation to the front case.

2. Install the optional USB port

Final Assembly

1. Place the back side upright (BC-250 should remain vertical)

2. Pre-position the front part on top and slide it in along the board

   • Make sure the fan cable is properly routed alog the heatsink, without being pinched

   • Same for the USB cable

3. Once the front and back are properly aligned, finish installing the fans. Walls should perfectly aligned. If not, you might have some cables in the way.

4. While still vertical, install the BC-250 board to its front-bracket support (1 screw on the top of the case)

5. Now it's time to plug the PCIe & ATX cables into the PSU, board and power switch

6. Connect the optional USB cable to the port

7. Nicely pack the cables and close the hatch

8. Test that everything powers-up correctly before installing the handle