Heatsink
Need a hand?
Average reply time: 1–3 days · Email is the fastest channel
Email us anything. Bug reports, feature requests, questions about a sensor reading, anything. We read every message. Reach us at support@heatsink.uk.
Before you write
If you can include the following with a bug report, we can usually diagnose it in one round:
- Your Mac model (Apple menu → About This Mac), e.g. "MacBook Pro 16-inch, M3 Pro"
- Your macOS version
- Heatsink version (Heatsink → About Heatsink)
- What you expected to see vs. what you actually saw — a screenshot is gold
Frequently asked questions
Why does each fan show a temperature instead of an RPM?
On Apple Silicon and macOS 14+, Apple gates fan-tach reads behind privileged entitlements that aren't available to sandboxed App Store apps. Rather than fabricate a fake RPM number, Heatsink binds each fan widget to a real on-die temperature sensor — the blade speed, glow color, and HOT/WARM/COOL badge are all driven by that zone's actual measured °C/°F. Hot = fan working harder. The metaphor matches physical reality without making anything up.
My MacBook Air shows "Fanless Chassis." Is that a bug?
No — every M-series MacBook Air is genuinely fanless and uses passive cooling. The dashboard shows a chip diagram with the live die temperatures instead of fan widgets, which is the honest representation of the hardware.
How do I switch to Fahrenheit?
Open Heatsink, then ⌘, (Cmd-comma) to bring up Settings. Under General → Display, pick Fahrenheit. The change propagates to every readout (dashboard, popover, menu bar, status footer, alert notifications) immediately.
How do I get a notification when my computer gets hot?
Settings → Alerts. Toggle "Notify when a sensor crosses a threshold," then set two thresholds — a warning tier and a critical tier — each with its own cooldown. Heatsink posts a local notification when the hottest sensor crosses either line. Per-tier cooldowns prevent notification spam during a long workload; the critical tier wins when both fire.
What does "PMU tdie6" mean? What about "PMU tcal"?
Hover any sensor row in the rail and the panel at the bottom of the rail will show a one-line description plus the live reading. In short:
- PMU tdieN — On-die temperature sensor on the SoC, reported by the Power Management Unit. Each numbered TDIE corresponds to a region of the chip (CPU clusters, GPU, neural engine).
- PMU tcal — A calibration reference, used internally for accuracy correction. Not the actual chip temperature.
- gas gauge battery — Battery cell temperature from the battery management controller.
- Tp0N — Apple Silicon proximity sensor near specific CPU/GPU cores.
- TC0… / TG0… — CPU / GPU temperatures (proximity, heatsink, or die) — common on Intel-based Mac computers.
Does Heatsink send any data to the cloud?
No. Heatsink does not have network access — its sandbox doesn't request it. There is no analytics, no telemetry, no cloud sync, no crash reporting that goes off-device. Sensor data, preferences, and history all stay on your computer. See the privacy policy for the full breakdown.
Can I run multiple Heatsink dashboards?
No — Heatsink is a single-window app. The dashboard is the same whether you open it from the Dock or from the menu-bar popover's "Dashboard" button. Two windows of the same data add no value, so we don't allow it.
Can Heatsink control my fan speed?
No — Heatsink is read-only. It visualises what's happening; it doesn't override macOS's thermal management. Fan-control utilities on macOS require kernel-level privileges, are not allowed in Mac App Store apps, and risk damaging your hardware if used carelessly. macOS already does a competent job balancing performance and thermals.
Heatsink doesn't show any sensors. What's wrong?
This usually means IOHID returned nothing for our sensor query. Causes we've seen:
- Running on a Mac model older than what we've tested — please email us with your Mac model
- A macOS update that changed sensor exposure — restart usually helps
- Sandbox issue from a corrupted preferences container — quitting and relaunching Heatsink usually fixes it
If none of that helps, send us your Mac model + macOS version and we'll look into it.
Reach us
support@heatsink.uk is the fastest way. We aim to reply within a few days.