CPU Overclock and Undervolt

CPU Overclock and Undervolt

The BC-250's CPU clock is also an SMU affair. SkillFishOS applies a persistent overclock/undervolt at boot via bc250_smu_oc, driven from /etc/bc250-smu-oc.conf by a one-shot systemd service (bc250-smu-oc.service).

The shipped profile

• 3700 MHz with Vid ≤ 1.325 V, 6 cores active, 85 °C thermal cap.
• 3700 MHz is this chip's verified-stable maximum under an 85 °C cap; 3800 throttles back to 3700 reproducibly. The Tuner section's CPU panel can sweep 3600–4000 MHz with Find my max; 4.0 GHz has been validated on good silicon.
• APU power sharing: under a combined CPU+GPU load the APU eases the CPU to ~3450 MHz to stay in the power budget — by design, not instability. Under CPU-only load it holds 3700 MHz pinned right at the 85 °C guard.

Thermal guard

skillfish-thermal-guard.service watches the k10temp CPU sensor; if it exceeds the cap (default 85 °C) it steps the SMU CPU frequency down by 100 MHz (and back up when it cools). This protects the silicon when the cooling can't keep up.

Undervolt

Undervolting lowers temperatures and power draw. The Tuner section's CPU panel offsets the factory voltage curve in 6.25 mV steps (0 = none, negative = less voltage). Too much makes the system unstable:

• Suggest UV proposes a starting offset for your target clock.
• Find my max sweeps 3600–4000 MHz to find the highest stable clock.
• Test 60 s stresses the current setting for a minute, with a countdown and a Stop button. Values under test are never written to disk until you keep them.

SMU contention

The governor and the OC tool both talk to the SMU. Service ordering (After=bc250-smu-oc.service) and a lock prevent them from clashing during apply/detect — don't poke the SMU from two places at once.

Profiles

Instead of a fixed CPU+GPU+fan table, the Control Center's Profiles section bundles a GPU ceiling, a CPU setting, a fan preset and a scheduler choice into one click: Quiet, Balanced, Performance, plus any you save yourself. See SkillFishOS Control Center and GPU Governor and Tuning for the GPU-side ceiling and its own Cautious/Balanced/Performance presets.