🌀 Only Fan Controller

The hottest fan controller for your server

An intelligent fan controller for Dell PowerEdge servers with simple threshold-based control, hysteresis to prevent oscillation, and a workload hints API for proactive cooling.

Features

• Multi-source Monitoring — CPU temps via IPMI, GPU temps via nvidia-smi
• Simple Threshold Control — Set CPU and GPU temperature thresholds, fans increase when exceeded
• Hysteresis — Configurable cooldown delay prevents fan oscillation at threshold boundaries
• Workload Hints API — External scripts can signal upcoming load for proactive cooling
• Web Dashboard — Real-time temps, fan speeds, and threshold visualization
• Constant Idle Speed — Quiet operation when temps are below thresholds

Quick Start

Docker (Recommended)

# Clone the repo
git clone https://github.com/sethpjohnson/only-fan-controller
cd only-fan-controller

# Copy and edit config
cp config.example.yaml config.yaml
nano config.yaml

# Run with docker-compose
docker-compose up -d

Docker with NVIDIA GPU Support

docker run -d \
  --name only-fan-controller \
  --restart unless-stopped \
  --gpus all \
  -e NVIDIA_VISIBLE_DEVICES=all \
  -p 8086:8086 \
  -v ./config.yaml:/etc/only-fan-controller/config.yaml:ro \
  -v ./data:/var/lib/only-fan-controller \
  only-fan-controller:latest

How It Works

1. Idle State: Fans run at idle_speed (default 20%) when both CPU and GPU are below their thresholds
2. Threshold Exceeded: When CPU > cpu_threshold OR GPU > gpu_threshold, fans increase by step_size per 5°C over
3. Cooldown: Fans only ramp down after staying below thresholds for cooldown_delay seconds (prevents oscillation)
4. Workload Hints: External scripts can set a minimum fan speed floor via the API

Web Dashboard

Access the dashboard at http://your-server:8086/dashboard/

Shows:

• CPU temperatures (all cores)
• GPU temperatures (all GPUs)
• Current fan speed and mode
• Temperature history graph with threshold lines
• Active workload hints

API Endpoints

GET /api/status

Returns current system state including thresholds:

{
  "cpu": { "Temps": [33, 34], "Max": 34 },
  "gpu": { "Devices": [{"name": "Tesla P40", "temp": 42}], "Max": 42 },
  "current_speed": 20,
  "zone": "idle",
  "cpu_threshold": 65,
  "gpu_threshold": 60,
  "idle_speed": 20
}

POST /api/hint

Register a workload hint for proactive cooling:

# Signal high GPU load starting (sets minimum fan speed to 45%)
curl -X POST http://localhost:8086/api/hint \
  -H "Content-Type: application/json" \
  -d '{
    "type": "gpu_load",
    "action": "start",
    "intensity": "high",
    "source": "whisper-transcription"
  }'

# Signal work complete (removes the floor)
curl -X POST http://localhost:8086/api/hint \
  -H "Content-Type: application/json" \
  -d '{
    "type": "gpu_load",
    "action": "stop",
    "source": "whisper-transcription"
  }'

Intensity levels:

• low — 25% minimum fan speed
• medium — 35% minimum fan speed
• high — 45% minimum fan speed

POST /api/override

Set a manual fan speed override:

curl -X POST http://localhost:8086/api/override \
  -H "Content-Type: application/json" \
  -d '{"speed": 50, "duration": 300, "reason": "testing"}'

DELETE /api/override

Clear manual override and return to automatic control.

GET /api/history?duration=3600

Get temperature/fan history for graphing.

Configuration

See config.example.yaml for all options.

Key Settings

fan_control:
  idle_speed: 20             # Base fan speed when cool (%)
  cpu_threshold: 65          # Increase fans when CPU exceeds this (°C)
  gpu_threshold: 60          # Increase fans when GPU exceeds this (°C)
  step_size: 10              # Fan increase per 5°C over threshold (%)
  cooldown_delay: 60         # Seconds below threshold before ramping down

Example: Quiet Home Server

fan_control:
  idle_speed: 15             # Very quiet
  cpu_threshold: 70          # Higher threshold for quieter operation
  gpu_threshold: 65
  cooldown_delay: 120        # Wait 2 minutes before ramping down

Example: Workstation with GPUs

fan_control:
  idle_speed: 25             # Slightly higher baseline
  cpu_threshold: 60          # More aggressive cooling
  gpu_threshold: 55
  cooldown_delay: 30         # Faster response

Integration Example

Wrap your GPU-intensive scripts to automatically manage cooling:

#!/bin/bash
# transcribe-with-cooling.sh

CONTROLLER_URL="http://localhost:8086"

# Signal GPU work starting
curl -s -X POST "$CONTROLLER_URL/api/hint" \
  -H "Content-Type: application/json" \
  -d '{"type":"gpu_load","action":"start","intensity":"high","source":"whisper"}'

# Wait for fans to ramp up
sleep 3

# Do the actual work
whisper --model large-v3 "$1"

# Signal complete
curl -s -X POST "$CONTROLLER_URL/api/hint" \
  -H "Content-Type: application/json" \
  -d '{"type":"gpu_load","action":"stop","source":"whisper"}'

Environment Variables

All config options can be overridden via environment variables:

Variable	Description	Default
IDRAC_HOST	iDRAC IP or "local"	from config
IDRAC_USERNAME	iDRAC username	root
IDRAC_PASSWORD	iDRAC password	-
GPU_ENABLED	Enable GPU monitoring	true
FAN_IDLE_SPEED	Base fan speed (%)	20
FAN_CPU_THRESHOLD	CPU temp threshold (°C)	65
FAN_GPU_THRESHOLD	GPU temp threshold (°C)	60
CHECK_INTERVAL	Seconds between checks	10
API_PORT	API/Dashboard port	8086

Unraid Installation

1. Copy unraid/only-fan-controller.xml to /boot/config/plugins/dockerMan/templates-user/
2. Configure via the Unraid Docker UI
3. Or use Community Applications (search "Only Fan Controller")

Requirements

• Dell PowerEdge server with iDRAC (tested on R730)
• iDRAC firmware with IPMI support
• For local mode: /dev/ipmi0 device access
• For remote mode: IPMI over LAN enabled in iDRAC settings
• For GPU monitoring: NVIDIA drivers and nvidia-smi

Building

# Build binary
go build -o only-fan-controller ./cmd/controller

# Build Docker image  
docker build -t only-fan-controller .

License

MIT

Credits

Inspired by tigerblue77/Dell_iDRAC_fan_controller_Docker