AMD BC-250 / BC250 ATX PSU Case

Intro

When I started with the BC-250 I printed an attractive and compact case that would incorporate a Meanwell LRS-350-12. However, my thermal performance was dreadful and the loud fan of the meanwell was a constant annoyance that was almost 50dB.

To improve the situation I removed the meanwell and replaced it with an old ATX PSU I had sitting around and punched a hole in the side and back of the case to power the BC250 and install a 60mm exhaust fan with a shroud.

Baseline results from old case with the ATX PSU outside of case

• Stock thermal paste and pads

• Oberon governor

• Ambient room temp 78f

• Idle fan noise 39dB

• Idle Temp 58c

Furmark 1080p:

• Temp under stress test 95c

• Thermal throttled at 2-3m

• Max fan noise 44dB

This was 'usable' as long as I took care with the more demanding games. However, it looked very messy with cables everywhere from the ATX PSU, and I figured I could do better. I looked around for an ATX PSU compatible case. While there were some, they all seemed to sacrifice air flow for compact design which I felt was at odds with my goals.

So I decided that I would have to just make one myself. I downloaded FreeCAD and began learning. I would like to extend a tremendous thank you to MangoJelly at this point, I could never have done this without your amazing tutorials (https://www.youtube.com/@MangoJellySolutions). Also a big thank you to https://www.printables.com/@torassk_228791 for providing an accurate BC-250 model which was extremely useful for virtual fitting.

And so I present my first FreeCAD project, and my first contribution to the 3D printing market

The BHN BC-250 ATX

It's big, it's boxy, it takes almost a week to print, and a local 3D print shop quoted me $360 to print it. I laughed at the offer and together with the prusaslicer cut function, plenty of E6000, and some patience, I printed this entirely on a single Prusa Mini+ with 2KG of PETG at 15% infill.

For those who go my route and cut it up, I suggest 5mm width and depth in the cut tool with 0.5mm tolerance.

Note: The Bottom, Rear, Front and Left plates should be glued together. The Right plate (with hole for top bolt) should not be glued to the main body.

Features

• Built around an ATX PSU with enough space to accomodate the bundled cords

• Us the stock IO plate and rear metal collar piece for mounting the BC-250

• 3x 120mm cold intake fans at the front, top and side to create a positive pressure airflow that moves over the length of both sides of the BC-250, exiting through the rear vents and PSU exhaust fan

• Fans are all powered and controlled by the BC-250's CPU fan header using a 3-way split cable

• Front panel has a 16mm hole for installing a momentary switch, the pictured model is https://a.co/d/05p05Q4u

  • My example has PSU MOBO cable jumped, board power jumper set to no-autostart, and moment switch is soldered to the board power button to duplicate the button's press. When PSU is turned on, the PSU fan will run and front button will light. One press of front button will power on the BC-250 and its fans. Pressing the button can also wake the BC-250 from sleep with long press to force shutdown. PSU will always be on unless manually switched off.

• Front Panel includes an 8x1mm round magnet recess for attaching personalized decals

• The top plate also features a recess with 8x1mm round magnet recesses for the fan cover bracket

• The fan bracket is DIY that you can fill with your own design or glue on mesh, etc. I've also included a sample bracket with the Steam logo

• Front decorative chip should be about 30-50mm and should include a 1x8mm recess for a magnet. I've included a sample chip with the Bazzite logo

Test Results in the BHN BC-250

• Stock thermal paste and pads

• Oberon governor

• Ambient room temp 80f

• Idle fan noise 34.5dB

• Idle Temp 54.4c (52c gpu)

Furmark 1080p

• Temp under stress test 95c

• Thermal throttled at 2-3m

• Max fan noise 40dB

2026-04-07 Updated test results

• Thermal Grizzly putty and Arctic MX-4 grease

• Oberon governor

• Ambient room temp 78f

• Idle fan noise 34.5dB

• Idle Temp 53c (50 gpu)

Furmark 1080p

• 90c reached after 3 minutes

• Thermal throttle at 5m20s

Conclusion

Idle temps improved, air flow at the exit vent is strong and cool, but thermals weren't much better under stress. I'll need to look into changing out the thermal paste/pads since I'm still on stock and they're likely skewing the result.

Updated: With the new thermal putty and paste idle temps further improved and time till throttle in furmark doubled from 2m to 5m. In game testing (FF15, 1080p@60hz, High) previously could reach throttle temps, but now I'm seeing 85c average with occasional spikes to 88c. 

Noise has decreased by 4-5dB, even with 3x the airflow! That is an almost 40% reduction to the human ear. At max fan speeds it's comparable to a floor fan on low/medium. A massive improvement over the constant irritation of the meanwell or an always-on 60mm fan.

Print design issues

• There is not enough space between the PSU and CPU fan to slide the top lid off as I originally intended. Removing the PSU screws to lean it outward is necessary when opening/closing the case. I would need to make the case 1cm wider to accomdate the intended slide action, or redesign the locking pegs of the top plate to avoid this.