The other app capable of controlling fans on Intel Macs in Windows — for free.
RPMac is a free and open-source fan-control utility for Intel-based Macs running Windows via Boot Camp. It talks directly to the Mac's SMC (System Management Controller) to monitor fan speeds and temperatures, and lets you set each fan to Automatic, Maximum, or a custom RPM. On T2 Macs, it talks to the slightly different SMC interface that the T2 chip exposes, controlling the fans like it would on any non-T2 Mac.
Designed as a lightweight, modern alternative to paid tools, RPMac includes hardware safety checks: it stays read-only on non-Apple hardware and never disables the SMC's built-in thermal protection.
Adding a point turns a plain ramp into "stay quiet until 58°, then ramp hard" — double-click to add, drag to shape, right-click to remove. The red dot shows where the fan is running on the curve right now.
 Fans Curve editor, 5-minute history and live temperatures |
 Sensors Grouped by CPU / GPU / system, with the raw SMC key |
 Settings Start with Windows · °C/°F · tray mode · overlay · themes |
 Four themes Dark · Light · Nature · Japan, applied instantly |
On-screen overlay (FRAPS-style, always on top — works over games in borderless/windowed mode):
 Vertical |
 Horizontal (compact) |
- Real-time fan RPM and temperature monitoring
- Per-fan control: Auto / Max / Manual RPM / temperature curve
- Graphical curve editor — as many points as you want (double-click to add, right-click to remove, drag to shape), with a live dot showing exactly where the fan is running on the curve right now
- Curve on the hottest sensor — instead of picking one sensor, let the fan follow whichever is hottest, so it ramps up when either the CPU or the GPU heats up
- Smooth fan changes — ignores tiny temperature wobbles so a curve doesn't make the fan audibly hunt up and down
- Emergency cooling — if any sensor reaches a temperature you set, every fan goes to maximum until it cools down
- Emergency shutdown — for a machine nobody is watching: if the heat holds even with the fans at maximum, or a fan that is being told to spin stays stopped, RPMac tells Windows to shut down cleanly instead of waiting for the CPU to cut power on its own. Off by default, and it never acts on a single reading
- Copy a curve to all fans, rescaled to each fan's own RPM range
- 5-minute history graph of temperature and fan speed, plus optional CSV recording of every reading
- Presets — save your fan setup as named profiles (e.g. Silent, Gaming) and switch with one click, from the app or the tray icon
- All sensors grouped by CPU / GPU / system, with their raw SMC keys (plus a full raw view)
- Name your own sensors — if your Mac exposes a sensor RPMac doesn't know, give it a name and it becomes usable everywhere: curves, "Highest temp", overlay, tray and CSV
- On-screen overlay (FRAPS-style): always-on-top, top-right corner, vertical or horizontal, with selectable fans/sensors
- Live temperature on the tray icon (highest sensor or a specific one) — or just the app icon, or nothing
- Themes: Dark / Light / Nature / Japan
- Temperatures in °C or °F
- Start with Windows + start minimized to tray
- Remembers your settings and re-applies them (including after sleep/resume)
- Command-line tool (
smccore.exe) for scripting fan control - Safety first — read-only unless it confirms a genuine Apple Mac with a valid SMC; clamps RPM to the SMC's own min/max
- Lightweight native UI — no runtime, no installer, nothing extra to install
- Free and open source (GPL-2.0)
No installer needed — it's a portable app.
- Go to the Releases page and download
RPMac-v1.8.0-windows.zip(under Assets). - Unzip it to any folder you like (e.g. your Desktop). Keep
RPMac.exe,RPMac.exe.config,smccore.exeandinpout32.dlltogether in the same folder. - Right-click
RPMac.exe→ "Run as administrator" (administrator rights are required to access the Mac's hardware/SMC). - Set each fan to Auto / Max / a custom RPM. Temperatures update live.
If Windows blocks it: RPMac is a small open-source app and isn't code-signed (a certificate costs a few hundred dollars a year), so Windows doesn't recognise it yet.
- SmartScreen ("Windows protected your PC") → More info → Run anyway.
- Smart App Control ("An Application Control policy has blocked this file") → it silently refuses to start. Either turn Smart App Control off in Windows Security → App & browser control, or build RPMac yourself from source (see Build).
- Antivirus: RPMac bundles InpOut32, a low-level I/O driver needed to talk to the SMC. Some antivirus tools flag this kind of driver as "potentially unwanted" because it grants hardware access — this is normal for fan-control utilities. The full source is in this repo; allow it if your AV blocks it.
None of this is a sign that something is wrong with the app — it's what happens to any unsigned utility that talks to hardware. Everything RPMac does is in this repository, and you can compile it yourself in a few seconds.
To uninstall, just delete the folder. Settings live in %APPDATA%\RPMac; if you enabled "Start with Windows", turn that toggle off first (or delete the RPMac scheduled task).
| Hardware | Status |
|---|---|
| Intel Macs (up to 2017) on Boot Camp | Should work (confirmed on MacPro6,1, MacPro3,1 and iMac17,1) |
| Intel Macs with T2 (2018-2020) | Requires PawnIO Unrestricted <=2.0.1 or >= 2.3.0 — the T2 uses a different SMC interface and needs PawnIO, but the driver has issues involving PawnIO 2.1.0 & 2.2.0 Unrestricted not actually disabling verification |
| Apple Silicon (M1+) | Not possible (no Boot Camp) |
| Non-Apple PCs | Read-only (writes are blocked) |
RPMac has been verified on five machines:
- Mac Pro (Late 2013) — model identifier
MacPro6,1- Intel Xeon CPU, dual AMD FirePro GPUs, single centrifugal system fan
- SMC fan/sensor values in
fpe2format, I/O base0x300
- Mac Pro (2008) — model identifier
MacPro3,1- Older Boot Camp in BIOS/CSM mode (where the Windows BIOS strings can be empty or lack "Apple") — RPMac still detects it via the SMC itself
- iMac (Retina 5K, 27-inch, Late 2015) — model identifier
iMac17,1- Intel Core i5-6500, AMD Radeon R9 M380, Windows 10 (Boot Camp)
- Fan control (Auto / Max / Manual / Curve) and temperature sensors both work; reported by a user (thanks @Bibihi98)
- Mac mini (Early 2009) — model identifier
Macmini3,1- Intel Core 2 Duo, NVIDIA GeForce 9400, single fan — running Windows 7 Pro SP1
- Manual RPM and temperatures both work; the oldest confirmed machine and the oldest confirmed Windows. Reported by @Mac-Apex
- MacBook Pro (16-inch, 2019) - model identifier
MacBookPro16,1- Intel Core i9-9880H, AMD Radeon Pro 5500M, dual fan — running Windows Server 2025 single-booted
- All of the features pretty much work @matthewyang204
On all four machines, reading sensors and controlling the fans (Auto / Max / custom RPM) work correctly.
Beyond the two Mac Pros above, RPMac has not been tested on other Mac models yet. That said, it is built on the standard Apple SMC interface that is common to virtually all Intel Macs, and the core auto-detects the number of fans and each key's data format. So it should work on most Intel Macs in Boot Camp, with these caveats:
- Fan control is the most portable part (it uses standard keys), so it has the highest chance of working everywhere.
- Temperature sensor names vary by model, so on other Macs some labeled sensors may be missing or wrong (use "Show all sensors (raw)" to see everything).
- T2 Macs (2018-2020) require PawnIO <=2.0.1 or >=2.3.0, see why above in the support chart.
- If the SMC does not respond with plausible values, RPMac automatically stays read-only and writes nothing.
RPMac has only been verified on a couple of Macs, so we would really appreciate your help confirming whether it works on yours — whether it works or not. Every report helps build a reliable compatibility list.
Please open an issue with:
- Mac model and year (e.g. "MacBook Pro 15-inch, 2015")
- Model identifier (e.g.
MacPro6,1) — find it in macOS under Apple menu > About This Mac > System Report, or on Windows in System Information - CPU and GPU (e.g. Intel Core i7, AMD Radeon)
- Number of fans RPMac detected
- Windows version
- What worked / what didn't — did fan control (Auto / Max / custom RPM) work? Were the temperatures correct?
- Any error messages or odd readings (a screenshot is great)
Even a quick "works fine on my iMac 2017" is hugely valuable. Thank you!
The release also includes smccore.exe, a small command-line tool for the same
SMC control, so you can drive the fans from scripts, Task Scheduler, etc. Run it from
an administrator terminal, with inpout32.dll in the same folder:
smccore.exe list show all fans (RPM, min, max, target)
smccore.exe temps show fans + temperature sensors
smccore.exe auto return ALL fans to automatic
smccore.exe max force ALL fans to maximum
smccore.exe set 2000 set ALL fans to 2000 RPM
smccore.exe auto 0 return fan 0 to automatic
smccore.exe max 0 force fan 0 to maximum
smccore.exe set 0 2000 set fan 0 to 2000 RPM
smccore.exe key TC0D dump a raw SMC key
Fan numbers are 0 .. N-1 (see list). RPM values are clamped to each fan's own
min/max. Like the GUI, it stays read-only and writes nothing on non-Apple hardware.
Prefer the GUI? Each fan has a built-in temperature curve (the "Curve" button) that ramps RPM between a min and max temperature on a sensor you choose. The command line is there for scripting/automation; you can also build your own ramp with
temps+set.
RPMac uses the public Apple SMC protocol (the same one documented in the Linux applesmc driver) over the SMC's I/O ports (DATA = 0x300, CMD = 0x304), via the InpOut32 ring-0 I/O bridge. It reads and writes standard SMC keys (FNum, F<n>Tg, FS! , temperature T... keys) and auto-detects each key's data type (fpe2, flt, ui*, sp*, ...).
- An Intel Mac running Windows (Boot Camp)
- Administrator rights (required for hardware I/O)
Compiles with the .NET Framework C# compiler already present on Windows — no Visual Studio needed.
The easiest way is the included build.bat (from the repo root):
build.bat
It compiles RPMac.exe and smccore.exe into build\ and copies inpout32.dll and
RPMac.exe.config next to them.
To compile RPMac.exe by hand instead, from the repo root:
mkdir build
csc /noconfig /target:winexe /platform:x86 ^
/win32manifest:src\gui\app.manifest ^
/out:build\RPMac.exe ^
/reference:System.dll ^
/reference:System.Core.dll ^
/reference:System.Xaml.dll ^
/reference:System.Windows.Forms.dll ^
/reference:System.Drawing.dll ^
/reference:WPF\WindowsBase.dll ^
/reference:WPF\PresentationCore.dll ^
/reference:WPF\PresentationFramework.dll ^
src\gui\Smc.cs src\gui\App.cs
csc.exe lives in %WINDIR%\Microsoft.NET\Framework\v4.0.30319. Keep inpout32.dll and
RPMac.exe.config next to RPMac.exe when you run it. (System.Windows.Forms and
System.Drawing are required — the tray icon uses them.)
GPL-2.0-only. See LICENSE.
RPMac's SMC code is derived from the Linux applesmc driver and smcFanControl — see NOTICE for credits. InpOut32 is bundled under the MIT license.
applesmc.c(Linux): Nicolas Boichat, Henrik Rydberg- smcFanControl: Hendrik Holtmann
- InpOut32: Phillip Gibbons
RPMac is provided "AS IS", without warranty of any kind, express or implied, including but not limited to the warranties of merchantability and fitness for a particular purpose, as stated in the GNU GPL-2.0.
- There is no guarantee that it will work on your Mac. It has only been tested on one model (see above).
- You use this software entirely at your own risk.
- The author and contributors are not responsible or liable for any damage of any kind — including but not limited to overheating, throttling, hardware failure, data loss, or any other problem — arising from the use or misuse of this software.
Notes on safety:
- Running the fan at maximum is safe for the hardware itself, but constant maximum speed increases noise, dust buildup and bearing wear over time.
- RPMac never disables the SMC's built-in hardware thermal protection — the SMC can still override the fans and throttle or shut down the machine to prevent overheating.
- Setting a fan too low under heavy load could let the machine run hot; RPMac clamps manual values to the SMC's own minimum/maximum, but use manual mode with care.