# Bc250 Ultimate Setup > Set up, tune, and stabilize Linux on an AMD BC-250 board (Cyan Skillfish, the cut-down PS5 APU, PCI 0x13fe / gfx1013). Installs the GPU governor that unpins the 1500 MHz lock, enables CPU C-states and P-states, raises the dynamic VRAM ceiling, and replaces ZRAM with zswap. Use when a user mentions BC250/BC-250, Cyan Skillfish, gfx1013, cyan-skillfish-governor, or reports that such a board stutters, crashes, or sits at a locked 1500 MHz. - Skill: `silkyland/bc250-ultimate-setup` (Agent Skill, multi-file: 3 files) - Install (CLI): `npx skillmds@latest add silkyland/bc250-ultimate-setup` - Raw SKILL.md: https://api.skillmd.com/api/skills/silkyland/bc250-ultimate-setup/raw - Safety review: pending (external: skill-scanner PASS, skillspector PASS) - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Coding & Dev Tools - License: CC-BY-SA-4.0 - Author: silkyland (https://skillmd.com/u/silkyland) - Updated: 2026-09-22 - Page: https://skillmd.com/skills/silkyland/bc250-ultimate-setup --- # BC-250 Ultimate Setup Bring an AMD BC-250 board from a fresh Linux install to a stable, tuned system. The BC-250 is an ex-crypto-mining board built around AMD's "Cyan Skillfish" APU: 6× Zen 2 cores, 24 RDNA2 CUs (`gfx1013`), and **16 GB of GDDR6 shared between CPU and GPU**. It runs Linux only. Out of the box it is unstable in specific, predictable ways — every one of them has a known fix. ## Mental model — the six things that make this board different 1. **No GPU governor exists by default**, so the GPU is pinned at 1500 MHz and idles around 105 W. Adding one is the single highest-impact change. 2. **No CPU C-states or P-states** are exposed by stock firmware. Idle power stays high and the CPU never scales. A community ACPI override fixes it. 3. **Unified memory.** The "VRAM split" is a *minimum* carve-out; the dynamic ceiling needs a kernel parameter, and there are two distinct crash modes. 4. **IOMMU is broken.** It must be disabled in BIOS or the board crashes. 5. **The GPU is usually `card1`, not `card0`.** Never hardcode a card index or a `/sys/class/drm/card0` path. Find it by PCI device id `0x13fe`. 6. **A GPU crash is a system crash.** CPU and GPU share one die — there is no isolating reset. Stability work is therefore about *avoiding* crashes: kernel version, voltage curve, and thermals. ## Non-negotiables - Never enable IOMMU in BIOS. - Never set the GPU minimum voltage below **700 mV** — it locks the GPU at 1500 MHz and silently defeats the governor. - Never use `Smokeless_UMAF` — it has bricked boards. - Avoid kernels **6.15.0–6.15.6** and **6.17.8–6.17.10** (GPU init fails). - Clear CMOS after every BIOS flash, and keep a fallback boot entry. - Never change RAM timings without a hardware flasher available. ## Workflow Always run detection first; never assume the machine's state. ``` detect → stage 1 → verify → stage 2 (reboot) → verify → optional tuning ``` ### 0. Detect (always, read-only, no root) ```bash bash scripts/detect.sh # or --json for machine-readable output ``` It reports distro, bootloader, initramfs, kernel, Mesa, the real GPU card index, VRAM split, C/P-states, swap/ZRAM/zswap, governor and sensor status, then prints the next steps that apply. **Decide from this output, not from assumptions.** Decision rules: - `kernel_broken: true` → stop, get off that kernel before anything else. - `bootloader`/`initramfs` determine which `stage2-boot.sh` branch runs. If either is `unknown`, do not run stage 2 — read `references/distro-notes.md` and apply the boot changes by hand. - `gpu_governor_running: false` → stage 1 is required. - `zram_active: true` or `ttm_pages_limit` unset → stage 2 is worth doing. ### 1. Core must-haves (no reboot) ```bash sudo bash scripts/stage1-core.sh --dry-run # preview sudo bash scripts/stage1-core.sh # apply ``` Installs monitoring tooling, loads the NCT6686D board sensors (`nct6683`, read-only), and installs + enables `cyan-skillfish-governor-smu` with an annotated conservative config. Idempotent; an existing governor config is backed up, never overwritten. Do **not** use the project's own `install.sh`: the release tarball omits the files it tries to copy. The script installs the binary and writes the unit. ### 2. Verify stage 1 ```bash bash scripts/verify.sh ``` The GPU clock should read 1000 MHz at idle and rise above 1500 MHz under load. If it stays at 1500, see `references/troubleshooting.md`. Note that a *light* workload legitimately stays at 1000 MHz — the default load target only ramps above 65 % GPU busy. ### 3. Boot-affecting changes (reboot required) ```bash sudo bash scripts/stage2-boot.sh # PREVIEW ONLY (default, safe) sudo bash scripts/stage2-boot.sh --yes # apply ``` Because this edits the bootloader, the default is a no-op preview. It: - installs the ACPI override (`SSDT-CST` = C-states, `SSDT-PST` = P-states, 800–3200 MHz) using whichever mechanism the detected initramfs needs; - adds `ttm.pages_limit` (≈12 GB dynamic VRAM) and zswap parameters to the kernel cmdline via the detected bootloader; - optionally replaces ZRAM with zswap(lz4) over a 16 GB swapfile — the swapfile is created and activated *before* ZRAM is disabled, so you are never left without swap; - backs every file it touches up to `/root/bc250-backup-/`. Useful overrides: ```bash ENABLE_ZSWAP=0 sudo bash scripts/stage2-boot.sh --yes # leave swap alone TTM_PAGES=3145728 sudo bash scripts/stage2-boot.sh --yes # different VRAM cap ``` Then **reboot**, and if it does not come up pick the fallback / LTS entry in the boot menu. ### 4. Verify stage 2, and keep verifying ```bash bash scripts/verify.sh # exits non-zero if a hard requirement failed ``` Expect: C-states on every CPU, P-states 800 MHz–3.2 GHz, `zswap` enabled, no ZRAM swap device, GPU governor running, and `nct6686` sensors visible. ## Optional tuning (only after the baseline is stable) - GPU ceiling — the default caps at 1850 MHz. To go higher, edit `[frequency-range] max` and add `[[safe-points]]`, then test 30+ minutes per step. Read `references/governor-tuning.md` first; the method (freeze → find voltage floor → widen) matters more than the numbers. - Fan curves — needs the out-of-tree `nct6687` driver plus CoolerControl; `references/cooling-and-power.md`. - 40 CU unlock / 8-core unlock / CPU OC — real gains, real risk. The 8-core unlock **requires** swapping to the 16-thread ACPI tables. See `references/kernel-matrix.md`. ## Worked example (real numbers) Reference run on CachyOS, kernel 7.2.4, limine, btrfs, stock cooling: | | before | after stage 1 | after stage 2 | |---|---|---|---| | GPU @ idle | 1500 MHz pinned | 1000 MHz @ 799 mV, ~40 W | same | | GPU @ load | 1500 MHz | 1850 MHz, 80–86 W, 61–64 °C | same | | CPU | no cpufreq at all | no cpufreq | idle 0.93 GHz ↔ load 3.49 GHz | | swap | ZRAM 14.8 GB | ZRAM 14.8 GB | zswap(lz4) + 16 GB swapfile | | `dmesg` resets/panics | — | 0 | 0 | The ACPI override shows up at boot as `ACPI: Table Upgrade: install [SSDT- HACK- P_CST3]` / `[SSDT- HACK- PSTATES]`. ## Troubleshooting Symptom → cause → fix lives in `references/troubleshooting.md`. The highest yield checks are always: kernel version, IOMMU, and whether CMOS was cleared. ## Where the detail lives | Read this | When | |---|---| | `references/kernel-matrix.md` | kernel choice, pinning, the optional unlocks | | `references/bios-and-vram.md` | BIOS musts, VRAM split, the two crash modes, `ttm.pages_limit` | | `references/governor-tuning.md` | governor options, config schema, voltage-curve method, hard limits | | `references/cooling-and-power.md` | PSU, temps, fans, sensors, CoolerControl | | `references/troubleshooting.md` | anything is broken | | `references/distro-notes.md` | non-Arch distros, what is tested vs documented | | `references/credits.md` | upstream projects and community links | | `assets/governor-smu-config.toml` | annotated starting config | ## Safety These scripts change the boot configuration. `stage2-boot.sh` is preview-first for that reason, backs up before writing, and prints its rollback steps. Review what it will do (`--dry-run`) before applying, and keep a bootable fallback entry. Numbers in the references are community defaults, not guarantees — silicon varies per board.