Hi Folks!

Thank you for your patience. It’s been quite a long journey developing the FlexATX version. I had to wait for another BC-250 board to arrive because my previous system suffered a brownout after I accidentally caused a short circuit while investigating the FlexATX PSU.

Introduction

A compact industrial-style enclosure designed for the AMD/ASRock BC-250.

This case was built around the original BC-250 heatsink, allowing the card to be installed without any heatsink modification or custom cooling hardware. The side-flow airflow design uses a large intake fan to push air directly through the stock heatsink for efficient cooling in a relatively compact enclosure.

The enclosure is designed for FlexATX power supply.

Despite the compact footprint, the case can also accommodate an optional internal 3.5-inch HDD for large local storage capacity for AAA title games — ideal for DIY steam machine or local LLM node.

Even with a single-fan cooling design, the enclosure maintains BC-250 temperatures around ~75°C under AAA gaming title load with 40CU enabled.

Features

• Fully 3D-printable enclosure

• Designed specifically for the AMD/ASRock BC-250

• Compatible with most FlexATX power supply

• Uses the stock BC-250 heatsink without modification

• Compact side-flow cooling layout

• Optional support for a 3.5-inch high-capacity HDD

Cooling Performance

Cooling performance is depending on frequency and enabled number of CUs.

For a reference, the case was tested using FurMark at 1920×1080 resolution with an ambient temperature of approximately 28°C (82°F).

Test Results:

• 24 CU @ 1500 MHz (stock configuration): 76°C GPU temperature

• 40 CU @ 1500 MHz (modified configuration): 85°C GPU temperature

• Backplate (measured with thermistor) 53~57°C

Kits Available

Official kit listing is available on eBay (currently U.S. only) This listing is owned by my family.

https://www.ebay.com/itm/236997099720

Updates

• 2026-09-21
  End cap panels with M16 switch hole
  

  
  

• 2026-09-13
  lan-party-handle-bar_v1
  

  ⚠ Beta version: This part is still under testing. The design may be updated based on testing and feedback.

  
  A simple carry handle for taking your BC-250 build to a LAN party.

  The handle uses the existing screw holes originally designed for the bottom legs, so no modification to the main body is required.
  

  Since the handle reuses the bottom leg mounting holes, the case will be upside down while being carried. This is intentional.

  
  Required hardware:

  • 4x M3 self-tapping screws for mounting the handle

  • #6-32 UNC screws for securing the base to the main body
    

• 2026-09-04
  body-rear-flex_v2.4_eps.stl
  
  Based on user feedback, added more clearance around the power connector area on the v2.4 rear body. This allows the use of thicker power cables or an EPS connector for powering the BC-250 instead of the standard 8-pin PCIe connector.
  
  The downside of this version is that the additional clearance may reduce the static pressure from the fan due to air leakage around the cable area. I recommend adding something like foam or sponge around the cables to seal the gap and maintain static pressure.
  

• 2026-08-02
  Classic front panel with magnetic rail. I ditched this design but it is still good.
   

• Rear body end with side vents for PSU inhale. Mostly applicable for Metalfish's PSUs.

• Fan mountable magnetic front cover v2 (body-cover-with-120mm-fan-magnetic-v2.stl)
  Moving 2nd fan more front aimed to give some cooling SSDs and IO ports. Also you can put logo coin as well.

• 2026-07-26
  Improved the FlexATX mounting holes to better accommodate dimensional differences between power supplies.

• 2026-07-11
  HDD mounter fan
  Based on user feedback, an additional fan mounter using HDD mounter. It is ideal for backplate cooling or SSD cooling. For backplate cooling, must combination with the v2.4 body. Three sizes fan can be mountable (40mm/60mm/80mm)

• 2026-07-06
  Fan guard
  Based on user feedback, a new fan guard is added.
  

• 2026-06-28
  Easy switch panel
  Based on a user request, I designed a new front panel compatible with the widely available ATX 24-pin jumper cable with a power switch.

  Since these cables are inexpensive and easy to find on Amazon, this is probably one of the simplest power switch solutions for the BC-250. No soldering or custom wiring is required.
  

  
  

• 2026-06-28
  v2.4 body (Experimental)
  Added ventilation openings to the front side of the back plate and increased rear fan support from 25 mm to 32 mm thickness.
  
  ⚠ Note: This version has not been thoroughly tested yet, and it may be significantly more difficult to print than the previous design. I’d also really appreciate it if someone could test whether the new ventilation openings actually improve cooling performance.
  

• 2026-06-27
  Fan edge snap ring
  Everyone can make the fan hole beautifully 😎 Please note that the ring is intentionally tight fit.

• A new 120mm fan mountable front panel (2026-06-21)

• Reduced magnet hole tightness on the magnetic front panel and rails (2026-06-17)

• Added body-rear-flex.stl, a new rear body supporting both standard and single-side I/O orientations with improved cable management (2026-06-13)

• Added power-btn-key-long.stl for improved switch click feel (2026-06-05)

• Added body-rear-ssio.stl with improved cable management (2026-06-03)

• Reduced the thickness of power-btn-base.stl (2026-06-03)

• Added a single-side I/O panel (2026-06-02)

• Fixed the M12 switch hole location to prevent interference with the front body (2026-06-01)

Print Notes

• PLA or PETG is recommended
  (high-temperature-resistant materials are not required)

• 5~10% infill is generally sufficient, but adding extra walls around self-tapping screw holes is recommended for better durability
  

Required items

For body

• M3 x 8mm self-tapping screws x17 (Zinc-coated one is probably better than stainless for assembly difficulty...)

• 120x120x25 12V PWM Fan with high static pressure (Typically Arctic P12 Pro (Amazon))

• #6 self tapping screw for fan mounting x4

• 8x2mm neodymium magnets x12 (Amazon)

• Long-reach (30~40cm) #2 Phillips screwdriver

• Quick bar clamp (for insert magnets)

For PSU installation

• FlexATX PSU x1 (The case designed with Apevia ITX-PFC500W (Amazon)) 

• #6-32UNC screws x3

For PSU power button (Option1: FlexATX PSU as a dumb 12V PSU)

1. Set BC-250 in Auto power on mode

2. One 12mm diameter latched push button (Amazon) to manually assert the PSU PS_ON signal, or make a custom power button using 8.6x8.6mm DPDT switch in this repo.

3. Connect the PSU PS_ON pin and GND pin to the switch. The PSU powers on while PS_ON is shorted to GND.
   

              FlexATX PSU
        ┌─────────────────────┐
        │                     │
        │   PS_ON o───────────┼─────o/ o─────┐
        │                     │    Switch    │
        │    GND  o───────────┼──────────────┘
        │                     │
        └─────────────────────┘

   When the switch is closed:
        PS_ON → GND => PSU turns ON

For PSU power button (Option2: FlexATX PSU with custom power control board (work in progress))

• Power control board with wake-on-lan (mine is here (Github))

For BC-250 installation

• #6-32 UNC mounting screws x1

For HDD mounting (Optional)

• #6-32 UNC HDD mounting screws x4 (for 3.5 inch HDD) or M3 screws x4 (SSDs)

• M3 18mm screw x2 and M3 nuts x2 for sliding mounter cramp

• USB 3.0 SATA Adapter with 12V power supply port (power supply is required only for 3.5 inch HDD) (Amazon)

• 5.5mm x 2.1mm male DC power connector (Amazon1 Amazon2)

Body Assembly

1. Install the cooling fan into the rear body section

2. Slide the BC-250 and PSU into the rear body, then connect 8pin PCIe power cables for the BC-250 and cooling fan (Red arrows)

3. Secure the rear panel to the PSU using three #6-32 UNC screws, then secure the rear body using four M3 self-tapping screws while organizing the cables.

4. Insert three neodymium magnets into the front cover rail. (The holes are designed to hold the magnets tightly without glue, but you may use superglue if necessary. The magnets can be inserted using bar clamps.) Then secure the rail to the rear body using two M3 self-tapping screws.

5. Slide the front body onto the BC-250 and PSU assembly while carefully managing the power and power button cables. Secure the front body to the rear body using five M3 screws. (You may need a long-reach Phillips screwdriver to tighten the screws.)

(Optional: Insert the HDD mount from the front side while organizing the cables during this step. After finding a suitable position for the HDD mount, tighten the clamp bolt on the bottom.)

6. Assemble the front cover rail with three neodymium magnets. Attach the rail to the front panel and secure it using two M3 screws. Then secure the front panel to the front body with four M3 screws (from front and back side). Secure the BC-250 to the front panel with #6-32 UNC screw.

(Optional: If you need to install a power switch, you may do so on the front panel during this step.)

7.  Slide a color stripe into the front cover (use super glue if necessary). Insert six neodymium magnets into the front cover.

HDD mounter assembly

Insert M3 nuts from the bottom of the HDD mount body, then insert M3×18 or M3×20 screws through both clamps.

Note: With a 3.5-inch HDD installed, the available space may become extremely tight. Based on my experience, only one orientation is practical: with the HDD’s rear side facing the front and the interface facing the rear. You will need to fit the USB-to-SATA adapter into the very narrow space between the PSU and the HDD. In this orientation, the USB cable may also be difficult to route to the BC-250 if the cable is too short.

Power button assembly (Optional)

The case includes the original power button used to trigger the ATX PSU’s PS-ON signal. You’ll need a small 8.6×8.6 mm DPDT latching switch (available on Amazon).

The assembly process is fairly straightforward: solder wires to the latching switch terminals, then crimp the wire ends to the Mini-Fit Jr. female terminals.

The switch pinout is typically like this:

Rear view of pins:
          1   2   3
          o   o   o

          o   o   o
          4   5   6

Electrical connection example:
   ON position:   1 ─ 2    4 ─ 5
   OFF position:  2 ─ 3    5 ─ 6

Finally, mount the assembled switch to the front panel using two M3 self-tapping screws.

Single side IO panel

Based on user feedback, a single-side I/O configuration has been requested. To address this, a new Single-Side I/O (SSIO) panel is now available. This panel allows the PSU to be installed on the same side as the BC-250 I/O panel.

Retrofitting an existing build is possible; however, assembly is considerably more difficult than with the original orientation.

Note: In the retrofit configuration, the HDD mount is not supported. I believe a newly designed rear body may allow HDD mounting in the SSIO configuration, but this has not been tested yet. I would appreciate it if someone could test the new rear body with the SSIO orientation and share the results.

Front cover with 120mm Fan 🆕

Based on user feedback, I designed a new front panel that supports an additional 120 mm fan.

This option may be especially useful for users who are looking for extreme cooling performance, such as for overclocking experiments or other high-load workloads.

To use this feature, you will need:

• body-rear-flex_v2.3

• body-front_v2.3

These updated parts include a dedicated cable-routing channel for the front fan.

(I believe it may still be possible to use the panel with the older v2.2 body with some modifications or creative cable routing, but it has not been tested.)

Assembly Tips

How to insert magnets to front cover / rails?

I think the magnet insertion step is the most difficult part of the assembly process. This guide shares my method for assembling this part. I recommend using a small quick bar clamp. You can find one at almost any hardware store. (I bought mine at Dollar Tree for $3.)

Apply a small amount of super glue inside the magnet hole (if needed), place the magnet on the hole, and then clamp them together.

After all magnets are inserted, place the part on a flat surface and clamp it together to ensure everything is flat and properly aligned.

Research Section 🧪

What is the best fan combination with this case?

The original concept of this case was to push air through the BC-250’s stock heatsink without modifying the card itself.

For that reason, my default recommendation has been the ARCTIC P12 Pro, as its relatively high static pressure is well suited for forcing air through the stock heatsink. (and it is relatively cheap!)

However, this raises an interesting question: there are plenty of excellent 120 mm fans on the market, so why limit ourselves to just one?

The P12 Pro has worked very well in my testing, but there may be quieter, more affordable, or more readily available alternatives. Comparing different fans under the same conditions could help us find even better options for different users and use cases.

I tested AT-120-K from ID-Cooling and P12 Pro's siblings a P12 Pro LN (Low-noise) this time.

The evaluation measured CPU temperature, GPU temperature, backplate temperature (using a thermistor), and noise level measured at a distance of 30 cm from the case. Benchmarking was performed using FurMark at 1080p, with an ambient room temperature of 28°C. The test system was configured with the BC-250 unlocked to 40 CUs running at 1500 MHz.

Base line: Arctic P12 Pro PST

After running FurMark for approximately 10 minutes, the ARCTIC P12 Pro PST maintained the following temperatures:

• CPU: 84.1°C

• GPU: 84.0°C

• Backplate: 47°C

• 51 db (30cm away from the FAN)

ID-COOLING AT-120K-K

For comparison, I replaced the ARCTIC P12 Pro PST with the ID-COOLING AT-120K-K and repeated the same benchmark under identical test conditions.

I really like the fan’s appearance—design looks great in the case too. But looks aren’t everything, so let’s see how it performs.

After approximately 10 minutes of running the benchmark, I obtained the following results:

• CPU: 87.0°C

• GPU: 86.9°C

• Backplate: 52°C

• 48.8 db (30cm away from the FAN)

Verdict: The fan is certainly usable, but it’s not the ideal choice for this case for cooling perspective. I like its design and overall appearance.

Arctic P12 Pro LN

This is the low-noise version of the P12 Pro. It looks almost identical to the standard P12 Pro, but the LN version has a lower maximum RPM to reduce fan noise.

In practice, it was noticeably quieter than the standard model. However, during the benchmark the GPU temperature climbed to around 99°C, so I stopped the test for safety.

Verdict: I do not recommend this fan for the BC-250.

Be careful not to confuse the P12 Pro PST LN with the standard P12 Pro PST. Their packaging looks almost identical, but the lower maximum fan speed of the LN model results in significantly worse cooling performance.

Foot note

This project is totally my Sunday project. However I took a lot of trial and error to develop.
If you’d like to support future improvements or to help buy me rolles of filaments (ko-fi), I’d really appreciate it. 🍺

I’m just happy people are enjoying hack a day!