Power, clock and thermal, under control.
A CPU under a sustained generative render heats up fast, and the firmware answers by throttling it hard — abruptly, mid-render, often into a reset. veizik runs a reactive governor that caps the clock before the chip reaches that point, adds explicit power modes and a supervised, opt-in overclock, and holds all of it inside a three-axis safety envelope. Every figure is measured on the boards.
A GPU’s thermal headroom, managed on a CPU.
The levers that keep a sustained render from throttling or browning out the board.
- A reactive governor, always on. A small supervisor samples the SoC temperature every two seconds and caps scaling_max_freq a step down as it warms, releasing it as it cools — so the chip settles below the firmware’s hard throttle instead of being cut abruptly mid-render. It is installed as an always-on service and every heavy render is also guarded in-process, so a render never runs thermally unprotected.
- Explicit power modes. --power max uses every core at full clock (an active cooler and a quality supply), balanced is the default, and eco runs fewer threads at a lower draw for a passive board or a marginal supply.
- A brownout axis. The Pi records undervoltage in get_throttled; veizik reads it, warns when the supply is marginal under load, and eco backs the current draw off — the single most common edge failure is a brownout reset, not heat.
- An opt-in overclock, supervised. An advanced, unsupported lever raises the clock ceiling within a clamped range; it only lifts the ceiling, and the thermal and power axes still bind and back it off, so an overclock the board cannot sustain degrades to a supported state rather than crashing.
Cap the clock before the throttle, release as it cools.
veizik’s shipped reactive-cap policy, with the measured outcome on the boards.
As the chip warms, the governor steps the clock cap down a band; as it cools, it releases. The bands below are veizik’s shipped default policy on a Pi Zero 2 W; the target is to hold the SoC under 76 °C, with margin below the 80 °C firmware hard-throttle where the board would otherwise be cut abruptly.
Measured (Pi Zero 2 W): the governor pre-emptively capped at 73.6 °C, held the chip under 76 °C with throttled=0x0, and the render completed — where an un-governed run drives past 80 °C and resets the board. On a Pi 5 with an active cooler and a stable supply the chip stays in a 47–78 °C band at its 2.4 GHz native clock, with throttled=0x0 in every counted run.
Explicit modes, and a supervised ceiling.
A supported performance control — and an advanced lever that stays inside the safety axes.
- Clamped and reversible. The ceiling is raised through the firmware config within a conservative range (arm_freq ≤ 3000 MHz, over_voltage ≤ 6, above the stock 2.4 GHz); an out-of-range request is refused, a backup of the config is kept, and a single command reverts it.
- Governor-supervised. Overclock lifts only the ceiling; the thermal cap and the brownout check still bind, so a sustained overclock that overheats or draws too much is pulled back automatically.
- Per-device, and honest about it. The Pi 5 (active cooler, quality PSU) has real headroom and is the natural target. A device that cannot overclock — the 512 MB Pi Zero 2 W, whose dominant failure mode is already a brownout — warns and does nothing rather than failing. It is opt-in, root-only, and off by default; veizik warrants nothing about it.
Thermal, power and memory — each degrades, none crashes.
Thermal, power and memory are three independent safety axes. None of them is a performance switch that can be set wrong: each detects its own limit and degrades to a supported state, so the render finishes instead of the board crashing.
A render that finishes beats a faster one that resets.
- Renders complete instead of crashing. The reason a long edge render fails is almost never the math — it is a thermal throttle or a brownout mid-run. Capping ahead of the limit is what turns a board that resets into one that finishes.
- Control without a cloud. Every one of these levers runs on the board; nothing about the power, the clock or the temperature leaves the device.
- The same model, tuned to the board you have. From a Pi 5 with an active cooler to a passively cooled 512 MB Zero 2 W, the power mode and the thermal envelope are settings, not a wall.