#steam-machine #bc250 #steamos #gaming #3d-printing #mandicreally #youtube # Overview Notes distilled from MandicReally's build of a DIY SteamOS console around a used **ASRock BC-250** crypto-mining card, mounted behind a TV. Final build cost **$828** to reproduce vs. **$1,428** for Valve's 2TB Steam Machine with controller — $600 cheaper [21:19](https://youtu.be/1fLg-coaVrQ?t=1279) — and it beat an official Steam Machine in the Cyberpunk 2077 benchmark by ~8% [18:59](https://youtu.be/1fLg-coaVrQ?t=1139). Key idea: the BC-250 is a suspected PlayStation 5 APU bin that can be unlocked from 6 cores / 24 CUs to 8 cores / 40 CUs [6:52](https://youtu.be/1fLg-coaVrQ?t=412). Getting real performance out of it is entirely a **cooling and airflow problem**, which is what most of the build addresses. Every bullet below links to the moment it was said in the video. # Resources - Video: [I Built a Steam Machine Faster and Cheaper Than Valve's](https://www.youtube.com/watch?v=1fLg-coaVrQ) — MandicReally, 2026-09-06, 23:15 - [[MandicReally DIY Steam Machine Transcript]] — full auto-captioned transcript - Free 3D models (BC-250 CAD model, Snowman cooler model, case): https://www.printables.com/@MandicReally/ - Benchmark comparison run on an official Steam Machine by [Snazzy Labs](https://www.youtube.com/@snazzy) [18:59](https://youtu.be/1fLg-coaVrQ?t=1139) - Detailed testing/overclocking data lives in the creator's members-only "Mission Debrief," not the main video [6:19](https://youtu.be/1fLg-coaVrQ?t=379) # Design ## Hardware | Part | Choice | Why | |---|---|---| | Compute | ASRock BC-250 | Ex-mining board, ~$200 at time of purchase, includes 16GB RAM + SSD [0:00](https://youtu.be/1fLg-coaVrQ?t=0) | | CPU cooler | Snowman MC78 (8 heat pipe, low profile) — caption says "MC-75-8" | $30, low profile fits the depth limit [5:14](https://youtu.be/1fLg-coaVrQ?t=314) | | Fans | Arctic P9 92mm PWM PST | Started with Arctic 8038 80mm — moved more air but far too loud [8:40](https://youtu.be/1fLg-coaVrQ?t=520) | | PSU | Apevia 500W Flex-ATX | Cheap, already used one in a prior ITX build, had a CAD model of it [12:46](https://youtu.be/1fLg-coaVrQ?t=766) | | Storage | 2TB NVMe SSD | Fits his current Steam library [11:03](https://youtu.be/1fLg-coaVrQ?t=663) | | Video out | UGREEN DisplayPort → HDMI (CEC + VRR) | Costs more than cheap adapters, but passes CEC so SteamOS can power on the TV and switch input [14:58](https://youtu.be/1fLg-coaVrQ?t=898) | | Network | Linksys Wi-Fi 6 extender → ethernet | Workaround for broken USB (see Troubleshooting) [16:10](https://youtu.be/1fLg-coaVrQ?t=970) | | Power switch | Wireless remote + latching relay inside the case | $12, gives couch power-on like a real console [20:48](https://youtu.be/1fLg-coaVrQ?t=1248) | | Case filament | Prusament PETG (structure), PC-CF (high-temp / high-strength parts and TV mounts) | Case sits in a warm pocket behind the TV [9:49](https://youtu.be/1fLg-coaVrQ?t=589) | | Thermal interface | Thermal Grizzly Basic Putty (pads), PhaseSheet (die) | Putty absorbs height variance where pads would go [5:14](https://youtu.be/1fLg-coaVrQ?t=314) | | TV | Hisense 65" 4K, 4K60 + VRR | Nothing special; matches what this hardware can drive [13:19](https://youtu.be/1fLg-coaVrQ?t=799) | ## Cooling strategy - Stock cooler was cut into **three pieces on a bandsaw** and hand-deburred, rather than replaced wholesale [4:06](https://youtu.be/1fLg-coaVrQ?t=246). - The former processor section gets relocated to the **back of the PCB** to cover all the GDDR6 chips as one plate — better than sticking individual heatsinks on each chip [4:39](https://youtu.be/1fLg-coaVrQ?t=279). - Its threaded bosses still poke through the original holes, so they become mounting points for the new cooler adapter [4:39](https://youtu.be/1fLg-coaVrQ?t=279). - The **VRM sections at each end stay intact** — reusing known-good mounting instead of a kludged assembly [5:14](https://youtu.be/1fLg-coaVrQ?t=314). - The Snowman's heatsink fins were **hand-bent open at the end**; they ship enclosed for downdraft, and this build needs air to pass straight through [8:05](https://youtu.be/1fLg-coaVrQ?t=485). - **Crossflow airflow, not downdraft.** Only 4" of depth behind the TV. The BC-250 was originally designed for front-to-back rack airflow, so this suits it [7:29](https://youtu.be/1fLg-coaVrQ?t=449). - Airflow path was prototyped with **cardboard ducting** before committing to a case design [8:05](https://youtu.be/1fLg-coaVrQ?t=485). ## Case - Shape came out looking like a video game raygun; driven by wrapping tightly around the hardware in limited depth [9:15](https://youtu.be/1fLg-coaVrQ?t=555). - **Modular sections** so fans, PSU, or the airflow path can be swapped without reprinting the whole case [9:15](https://youtu.be/1fLg-coaVrQ?t=555). - The section over the heatsink is the one he most expects to iterate on — currently half-covered to force air through the fins before venting [12:13](https://youtu.be/1fLg-coaVrQ?t=733). - Assembly: brass heat-set inserts, plus **raised alignment ridges between sections** rather than relying on flat mating faces [10:27](https://youtu.be/1fLg-coaVrQ?t=627). - Magnetic fan filter on the front intake [12:46](https://youtu.be/1fLg-coaVrQ?t=766). - Design prioritizes airflow over serviceability — parts have to be shoehorned in [11:38](https://youtu.be/1fLg-coaVrQ?t=698). - Mounts sandwich between the TV and its VESA mount; printed in PC-CF [13:51](https://youtu.be/1fLg-coaVrQ?t=831). The machine wobbled on those alone, so an extra top bracket was VHB-taped to the back of the TV [14:22](https://youtu.be/1fLg-coaVrQ?t=862). ## Making the CAD model Existing BC-250 models online lacked the memory chips on the back and the CPU on the front [2:18](https://youtu.be/1fLg-coaVrQ?t=138). His method [2:55](https://youtu.be/1fLg-coaVrQ?t=175): 1. Set the PCB on a bench with a ruler and a framing square alongside for reference. 2. Shoot it from a ladder with a phone **telephoto** lens to minimize perspective skew. 3. Import that photo into Autodesk Fusion as a canvas and draw around it. 4. Combine with a lot of manual measuring. # Configuration Final settings he landed on [18:21](https://youtu.be/1fLg-coaVrQ?t=1101): | Setting | Value | |---|---| | CPU clock | 3.85 GHz | | GPU clock | 2.2 GHz | | GPU compute units | 40 (unlocked from stock 24) | | CPU cores in use | 6 (8 unlockable, but not used — see Decisions) | | GPU temp under load | ~77 °C, throttles at 85 °C [17:50](https://youtu.be/1fLg-coaVrQ?t=1070) | Cyberpunk 2077 in-built benchmark, same presets throughout: | Config | Avg FPS | |---|---| | BC-250, stock | 34.84 [18:21](https://youtu.be/1fLg-coaVrQ?t=1101) | | BC-250, overclocked + unlocked | 68.74 [18:59](https://youtu.be/1fLg-coaVrQ?t=1139) | | Valve Steam Machine (run by Snazzy Labs) | 63.65 [18:59](https://youtu.be/1fLg-coaVrQ?t=1139) | He notes this is **one benchmark in one game**, and that Valve would likely win others — plus Valve has a warranty and better connectivity [19:37](https://youtu.be/1fLg-coaVrQ?t=1177). # Decisions - **Don't bother unlocking the extra 2 CPU cores for gaming.** He got all 8 working, but found the workload is GPU-limited: run-to-run variance swamped any gain, while CPU temps rose **5–10 °C** and power draw increased. He speculates it could matter for a local LLM or other compute workload, not games [20:11](https://youtu.be/1fLg-coaVrQ?t=1211). - **Cut the stock cooler rather than buy new heatsinks** — reuses proven mounting hardware and gets a single large plate over the GDDR6 [4:39](https://youtu.be/1fLg-coaVrQ?t=279). - **Pay up for a CEC-capable DP→HDMI adapter.** He calls this the step DIY builds usually hand-wave away, and it's what makes it feel like a console [15:35](https://youtu.be/1fLg-coaVrQ?t=935). - **Skipped a Wi-Fi 7 extender** — would have blown the budget, and the BC-250 only has a 1GbE port anyway [16:42](https://youtu.be/1fLg-coaVrQ?t=1002). - **Quieter fans over more airflow.** Arctic 8038s moved "a ton of air" but were "angry"; P9s move less but sound far better, and there was thermal headroom to spare [8:40](https://youtu.be/1fLg-coaVrQ?t=520). # Troubleshooting - **Flaky USB 3.0 ports.** His used board has only two USB 3.0 ports; one falls back to USB 2.0 speeds with anything plugged in, the other connects at full speed but drops in and out. He suspects a controller issue, spent days on it, and never fixed it — so no USB Wi-Fi adapter [15:35](https://youtu.be/1fLg-coaVrQ?t=935). Workaround: Linksys Wi-Fi 6 extender joined to the house network, ethernet cable from it to the board [16:10](https://youtu.be/1fLg-coaVrQ?t=970). He frames this as **the risk of buying used hardware** [16:42](https://youtu.be/1fLg-coaVrQ?t=1002). - **Not every BC-250 unlocks.** These are believed to be chips that didn't make Sony's cut, so core/CU unlocking isn't guaranteed to be stable on a given board — his happened to work [6:52](https://youtu.be/1fLg-coaVrQ?t=412). - **Support the TV while installing the VESA sandwich mounts.** He nearly dropped his [13:51](https://youtu.be/1fLg-coaVrQ?t=831). - **Noise:** measured **+5 dB** over room baseline with fans at 100%, which he calls noticeable in a quiet room but effectively masked by game audio, and fans don't sit at 100% in practice [17:15](https://youtu.be/1fLg-coaVrQ?t=1035). # Price | Item | Cost | |---|---| | Full rebuild cost today (board, 2TB SSD, all parts, filament included) | $828 [21:19](https://youtu.be/1fLg-coaVrQ?t=1279) | | Valve Steam Machine, 2TB, with controller | $1,428 [21:19](https://youtu.be/1fLg-coaVrQ?t=1279) | | Difference | $600 cheaper | ==Caveat on the board price:== he actually paid **$160** for the BC-250 a couple of months before filming; by upload it was **$300**, because other YouTubers covering the board drove demand up. At his original price the build was closer to 50% of Valve's [21:55](https://youtu.be/1fLg-coaVrQ?t=1315). ==Expect BC-250 pricing to have moved again — verify current eBay pricing before budgeting.== # TODO - ==Confirm the Snowman cooler part number — video description says "Snowman MC78," transcript captions render it "MC-75-8."== - ==Fan model: description lists "Arctic P92," captions say "P9 92mm PWM PST." Same fan, but confirm exact SKU/PST variant before ordering.== - ==Check whether a current BC-250 at ~$300 still beats a used mini PC / Steam Machine on price-per-frame.== - ==Download the BC-250 CAD model and case STLs from Printables if pursuing this build.== # References - [[MandicReally DIY Steam Machine Transcript]]