Safety model
Extra cooling that fails closed
System is Smart Breeze’s default mode and its fallback. Smart Boost engages only when your curve calls for extra cooling and never starts below the speed macOS was already requesting.
What Smart Breeze verifies
- Requests are clamped to each fan’s firmware-reported minimum and maximum.
- Fan-mode and target changes are read back from AppleSMC.
- A failed write requests an all-fan rollback instead of reporting success.
- A helper restart performs a verified System handoff before accepting new control.
- Stale, replayed, oversized, expired, or excessive helper requests are rejected.
Independent safeguards
While manual fan ownership may be active, Smart Breeze sends a heartbeat to its privileged helper. If no heartbeat arrives for about 10 seconds, an independent supervisor requests verified System control. Missing temperature data for about 10 seconds triggers the same fallback.
At 95 °C, the helper requests each fan’s firmware-reported maximum on qualified hardware. After temperature remains at or below 88 °C for about 20 seconds, it releases the fans to System.
Recovery behavior
Smart Boost may automatically re-arm after a verified wake, power-profile change, helper interruption, or temporary ownership handoff. macOS remains in control during recovery. Max and per-fan Manual modes fail closed and generally require deliberate action after an interruption.
Important limitations
These safeguards reduce risk; they cannot turn Apple’s private SMC interface into a supported API or guarantee lower temperatures, improved performance, or protection from hardware failure. macOS and firmware remain the final thermal safety layer.
Keep System selected unless you intentionally want extra cooling. Use Manual mode only while diagnosing a problem.