Short answer
Start with Any Sensor when more than one component can lead the heat pattern or when you have not yet established a stable driver. Choose CPU or GPU only when the corresponding aggregate category is available and repeatedly tracks the workload phase you care about. Choose Battery for a battery-centered test, not as a general proxy for chip load. Build 22 labels and falls back to the hottest available reading when a specifically selected category is unavailable. Memory can appear in monitoring and the Thermal Sensors explorer when available but is not a selectable curve source in Build 22.
The source decides when the curve moves
A curve has no effect until a temperature is fed into it. In Smart Breeze, the selected source determines the temperature used for first-point activation, interpolation along the curve, and release timing. Two identical point sets can therefore behave differently when one watches CPU and the other watches Any Sensor.
The internal reading is also not the Mac’s external case temperature. Apple cautions that third-party temperature utilities do not measure the enclosure temperature and should not be used to diagnose a hardware issue. Use Apple Diagnostics or service when the symptom suggests a fault.
What each Build 22 option means
| Source | Useful starting context | Main caveat |
|---|---|---|
| Any Sensor | Mixed workloads, changing CPU/GPU leadership, or first-pass observation | The hottest available category can change, so correlate it with the named live readings and workload phase. |
| CPU | A repeatable CPU-heavy phase whose CPU aggregate is available | It may not represent GPU, battery, or another component leading the thermal pattern. |
| GPU | A repeatable graphics or compute phase whose GPU aggregate is available | Some workloads are mixed; CPU or another available category may lead at a different phase. |
| Battery | A battery-temperature investigation with an available battery reading | It is not a general substitute for CPU/GPU load and can respond on a different timescale. |
| Memory | Monitoring and diagnostics when discovered | It is not selectable as the controlling source in Build 22. |
“Any Sensor” is the UI label for Smart Breeze’s hottest-available source. It is a conservative discovery default, not proof that every sensor on the Mac is exposed or that the displayed category is the only thermally relevant component.
Choose by repeated correlation, not by intuition
- Stay in System and begin the exact workload you want to characterize.
- Watch CPU, GPU, Battery, and hottest available across warm-up, sustained work, and cool-down.
- Identify which available category rises and falls consistently with the phase you care about, not simply which produced the single highest number.
- Repeat once under the same power source and macOS power mode to see whether the relationship is stable.
- Choose that category, or keep Any Sensor if component leadership changes across the run.
- Test the curve with the same workload and confirm that activation and release occur for understandable reasons.
Understand fallback before trusting the label
If CPU, GPU, or Battery is selected but that category is unavailable, Build 22 labels the condition and uses the hottest available reading. This preserves a temperature input when one exists; it does not manufacture the missing category. The controlling-sensor label in the dashboard is therefore part of the evidence for every run.
| Observed state | Interpretation | Next action |
|---|---|---|
| Selected category has a live value | The chosen aggregate is available for this snapshot. | Correlate it with the workload before deciding it is representative. |
| Smart Breeze labels hottest fallback | The selected aggregate is unavailable; another available category drives the curve. | Either accept Any Sensor deliberately or choose another consistently available category. |
| All temperatures unavailable or stale | There is no valid input for temperature-based control. | Build 22 requests System; copy diagnostics and troubleshoot monitoring. |
| Memory is unavailable | That optional monitoring aggregate was not discovered. | Do not treat the dash as a zero-degree reading or as a fan-control failure. |
Validate the source with history and ownership
Use the 15-minute history as a chronology, not as a scorecard. The temperature lane and fan-speed lane use separate honest scales. Align the sensor rise, curve activation, target change, actual response, workload end, release threshold, and System handoff. A source is useful when that story repeats and the reasons remain legible.
- Did the source rise before or during the workload phase, rather than long after it?
- Did it cross the first point consistently across repeated runs?
- Did actual fan RPM approach the requested target while Smart Breeze owned control?
- Did the source cool below the release threshold and remain there for the configured cooldown?
- Did the dashboard verify macOS ownership at the end?
Then tune the shape with the repeatable best-curve method, or return to the curve fundamentals if target percentages or release behavior are still unclear.
Separate sensor support from fan-control support
Temperature discovery and physical fan control are two independent compatibility questions. A fanless Mac can expose useful temperatures but has no fans to control. A fan-equipped Mac can expose readings while remaining System-only because its SMC write path has not passed exact-model qualification. Build 21 had a documented M5 MacBook Air issue where a missing fan-count key stopped the snapshot before independent temperatures were read. Build 22 changes that path and adds an individual sensor explorer, but physical verification on that M5 Air remains pending.
Sources and scope
Primary references and product scope
Apple sources define macOS and hardware behavior. Smart Breeze behavior is checked against the signed release and its documented safety boundaries. Where a conclusion is an inference or a method, this guide labels it as such.
- Smart Breeze compatibility and sensor-category limitsSmart Breeze
- Smart Breeze Build 22 known issuesSmart Breeze
- Keep your Mac laptop within acceptable operating temperaturesApple Support
- Use Apple Diagnostics to test your MacApple Support
Missing a reading?
Help qualify the exact model instead of guessing.
Fan-equipped and fanless Apple-silicon owners can apply for staged hardware testing. Applying does not unlock fan writes in the public build.