ryujin-iii-fand

Fan curve daemon for ASUS ROG Ryujin III AIO liquid coolers on Linux.

Single-file Python daemon. Reads liquid temperature via USB HID, interpolates piecewise linear fan/pump curves with hysteresis, and optionally drives the LCD HW monitor display with live sensor data.

Supported devices

PID	Device
0x1ADA	ROG Ryujin III White Edition
0x1AA2	ROG Ryujin III 360
0x1ADE	ROG Ryujin III EVA Edition
0x1BCB	ROG Ryujin III Extreme
0x1B4F	ROG Ryujin III (variant)

Dependencies

• Python 3.10+
• python-hidapi (Arch: sudo pacman -S python-hidapi)

Install

sudo make install
sudo make enable start

Uninstall

sudo make uninstall

Usage

# Run with cyberpunk HW monitor display (default)
ryujin-iii-fand --display cyberpunk

# Run with galactic background
ryujin-iii-fand --display galactic

# Fan control only (no display)
ryujin-iii-fand

# Custom curves from config file
ryujin-iii-fand --config /etc/ryujin-iii-fand.conf

# Dump sensor readings and exit
ryujin-iii-fand --dump

Configuration

Create a config file with [fan] and [pump] curve sections. Each line is temperature = duty_percent. Linear interpolation between points.

[settings]
spindown = 2    # degrees C hysteresis before ramping down

[fan]
# temp (C) = duty (%)
0 = 0
60 = 30
80 = 40
100 = 70

[pump]
20 = 20
50 = 40
65 = 55
70 = 65

Default curves match the Armoury Crate stock profiles.

Display styles

Style	Description
cyberpunk	Animated cyberpunk neon background
galactic	Animated space/nebula background
custom	Solid black background

How it works

• Polls liquid temperature every 3 seconds (configurable with --interval)
• Interpolates fan and pump duty from the curve with hysteresis
• Sends EC 1A HID command to set duties (ctrl_src=1 for host control)
• Optionally sends EC 52/EC 53 to update LCD HW monitor display
• On shutdown (SIGTERM), sends ctrl_src=0 to release pump back to internal Asetek controller
• On sleep (SIGUSR1), sends EC 5C 20 standby command
• On wake (SIGUSR2), sends EC 5C 10 to resume display

The embedded fan has no internal controller and must always be host-driven. The pump has an internal Asetek controller that takes over when ctrl_src=0.

Files

File	Installed to	Purpose
ryujin_iii_fand.py	/usr/local/bin/ryujin-iii-fand	Daemon
ryujin-iii-fand.service	/etc/systemd/system/	systemd unit
ryujin-iii-sleep.sh	/usr/lib/systemd/system-sleep/	Sleep/wake hook
99-ryujin.rules	/etc/udev/rules.d/	USB permissions
ryujin-iii-reset.sh	—	Virtual USB replug (manual)

License

GPL-3.0