Dell iDRAC Fan Controller

Intelligent, gradual fan speed control for Dell PowerEdge servers — keeps your server quiet under light load while automatically scaling up as temperatures rise, and handing off to Dell's built-in protection when it matters most.

Unlike simple on/off fan controllers that jump between a fixed quiet speed and full Dell control, this controller scales fan speed continuously across a configurable temperature range. Three defined zones give you fine-grained control over noise, airflow, and thermal safety.

Table of contents

1. How it works
2. Container console log example
3. Requirements
4. Supported architectures
5. Download Docker image
6. Usage
7. Parameters
8. Troubleshooting
9. Contributing
10. License

How it works

Three-zone fan control

Fan speed is determined by three zones based on CPU temperature:

Zone	Condition	Behaviour
Quiet	temp ≤ LOWER_THRESHOLD	Fans held at FAN_SPEED_MIN
Dynamic	LOWER_THRESHOLD < temp < UPPER_THRESHOLD	Fan speed scales linearly between FAN_SPEED_MIN and FAN_SPEED_MAX
Dell default	temp ≥ UPPER_THRESHOLD	Dell's built-in dynamic control takes over for maximum cooling

Fan speed curve

The chart below uses the default threshold and speed values as an example:

xychart-beta
    title "Fan speed vs CPU temperature (example: lower=45°C, upper=75°C, min=5%, max=50%)"
    x-axis "CPU Temperature (°C)" [30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80]
    y-axis "Fan Speed (%)" 0 --> 100
    line [5, 5, 5, 5, 11, 18, 25, 33, 40, 50, 50]

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Above the upper threshold the chart shows FAN_SPEED_MAX but in practice Dell's dynamic control takes over and fans ramp freely beyond that point.

State machine

stateDiagram-v2
    direction LR

    [*] --> Dell_Default

    Dell_Default : Dell Default\n(safety)
    Quiet : Quiet\n(FAN_SPEED_MIN)
    Dynamic : Dynamic\n(scaled FAN_SPEED_MIN → FAN_SPEED_MAX)

    Dell_Default --> Quiet : temp ≤ lower threshold
    Dell_Default --> Dynamic : lower < temp < upper

    Quiet --> Dynamic : temp > lower threshold
    Quiet --> Dell_Default : temp ≥ upper threshold

    Dynamic --> Quiet : temp ≤ lower threshold − hysteresis
    Dynamic --> Dell_Default : temp ≥ upper threshold

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Hysteresis: when returning from Dynamic to Quiet, the temperature must drop 2°C below the lower threshold. This prevents rapid fan oscillation when the CPU hovers near the boundary.

Main loop

flowchart TD
    A([Container start]) --> B{ENABLE_DELL_CONTROL\nON_STARTUP?}
    B -- true --> C[Apply Dell default\nfan control]
    B -- false --> D
    C --> D[Validate env vars\nDetect server model\nProbe sensors]
    D --> E[Read all sensors\nsdr list full]
    E --> F{IPMI\nsucceeded?}
    F -- no --> G[Increment failure\ncounter]
    G --> H{Failures ≥\nMAX_CONSECUTIVE?}
    H -- yes --> I([Apply Dell default\nand exit])
    H -- no --> E
    F -- yes --> J[Take max of all\nCPU temperatures]
    J --> K{Which\nzone?}
    K -- temp ≤ lower --> L[Apply FAN_SPEED_MIN]
    K -- between thresholds --> M[Calculate scaled speed\nlinear interpolation\nround up]
    M --> N[Apply scaled speed]
    K -- temp ≥ upper --> O[Apply Dell default\nfan control]
    L --> P[Print status row]
    N --> P
    O --> P
    P --> Q[Sleep CHECK_INTERVAL]
    Q --> E

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Container console log example

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Requirements

iDRAC version

This Docker container only works on Dell PowerEdge servers that support IPMI commands, i.e. < iDRAC 9 firmware 3.30.30.30.

To access iDRAC over LAN (not needed in "local" mode) :

1. Log into your iDRAC web console

2. In the left side menu, expand "iDRAC settings", click "Network" then click "IPMI Settings" link at the top of the web page.

3. Check the "Enable IPMI over LAN" checkbox then click "Apply" button.

4. Test access to IPMI over LAN running the following commands :

apt -y install ipmitool
ipmitool -I lanplus \
  -H <iDRAC IP address> \
  -U <iDRAC username> \
  -P <iDRAC password> \
  sdr elist all

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Supported architectures

This Docker container is currently built and available for the following CPU architectures :

• AMD64
• ARM64

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Download Docker image

• Docker Hub
• GitHub Containers Repository

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Usage

1. with local iDRAC:

docker run -d \
  --name Dell_iDRAC_fan_controller \
  --restart=unless-stopped \
  -e IDRAC_HOST=local \
  -e FAN_SPEED_MIN=5 \
  -e FAN_SPEED_MAX=50 \
  -e CPU_TEMPERATURE_LOWER_THRESHOLD=45 \
  -e CPU_TEMPERATURE_UPPER_THRESHOLD=75 \
  -e CHECK_INTERVAL=60 \
  --device=/dev/ipmi0:/dev/ipmi0:rw \
  jeffsnyder0/dell_idrac_fan_controller:latest

2. with LAN iDRAC:

docker run -d \
  --name Dell_iDRAC_fan_controller \
  --restart=unless-stopped \
  -e IDRAC_HOST=<iDRAC IP address> \
  -e IDRAC_USERNAME=<iDRAC username> \
  -e IDRAC_PASSWORD=<iDRAC password> \
  -e FAN_SPEED_MIN=5 \
  -e FAN_SPEED_MAX=50 \
  -e CPU_TEMPERATURE_LOWER_THRESHOLD=45 \
  -e CPU_TEMPERATURE_UPPER_THRESHOLD=75 \
  -e CHECK_INTERVAL=60 \
  jeffsnyder0/dell_idrac_fan_controller:latest

docker-compose.yml examples:

1. to use with local iDRAC:

version: '3.8'

services:
  Dell_iDRAC_fan_controller:
    image: jeffsnyder0/dell_idrac_fan_controller:latest
    container_name: Dell_iDRAC_fan_controller
    restart: unless-stopped
    environment:
      - IDRAC_HOST=local
      - FAN_SPEED_MIN=5
      - FAN_SPEED_MAX=50
      - CPU_TEMPERATURE_LOWER_THRESHOLD=45
      - CPU_TEMPERATURE_UPPER_THRESHOLD=75
      - CHECK_INTERVAL=60
    devices:
      - /dev/ipmi0:/dev/ipmi0:rw

2. to use with LAN iDRAC:

version: '3.8'

services:
  Dell_iDRAC_fan_controller:
    image: jeffsnyder0/dell_idrac_fan_controller:latest
    container_name: Dell_iDRAC_fan_controller
    restart: unless-stopped
    environment:
      - IDRAC_HOST=<iDRAC IP address>
      - IDRAC_USERNAME=<iDRAC username>
      - IDRAC_PASSWORD=<iDRAC password>
      - FAN_SPEED_MIN=5
      - FAN_SPEED_MAX=50
      - CPU_TEMPERATURE_LOWER_THRESHOLD=45
      - CPU_TEMPERATURE_UPPER_THRESHOLD=75
      - CHECK_INTERVAL=60

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Parameters

Parameters

Parameter	Required	Default	Description
IDRAC_HOST	Yes	local	local for direct IPMI access, or the iDRAC IP address for LAN access
IDRAC_USERNAME	LAN only	root	iDRAC username
IDRAC_PASSWORD	LAN only	calvin	iDRAC password
FAN_SPEED_MIN	Yes	5	Minimum fan speed (%) applied when CPU temp is at or below the lower threshold
FAN_SPEED_MAX	Yes	50	Maximum fan speed (%) before handing control back to Dell
CPU_TEMPERATURE_LOWER_THRESHOLD	Yes	45	Temperature (°C) at or below which minimum fan speed is applied
CPU_TEMPERATURE_UPPER_THRESHOLD	Yes	75	Temperature (°C) at or above which Dell default fan control is restored
CHECK_INTERVAL	Yes	60	Seconds between each sensor read and fan speed update
ENABLE_DELL_CONTROL_ON_STARTUP	No	false	If true, restores Dell default fan control before the first temperature read. Useful as an extra fail-safe on container restart.
DISABLE_THIRD_PARTY_PCIE_CARD_DELL_DEFAULT_COOLING_RESPONSE	No	false	Disable Dell's extra cooling response for non-Dell PCIe cards. Gen 13 and older only.
KEEP_THIRD_PARTY_PCIE_CARD_COOLING_RESPONSE_STATE_ON_EXIT	No	false	If false, resets PCIe card cooling response to Dell default on exit. Gen 13 and older only.

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Troubleshooting

If your server frequently switches back to Dell default fan control:

1. Check Tcase (case temperature) of your CPU on the Intel Ark website and set CPU_TEMPERATURE_UPPER_THRESHOLD to a slightly lower value than Tcase.
2. Raise FAN_SPEED_MAX to increase airflow in the dynamic range, which helps keep temps below the upper threshold.
3. Lower CPU_TEMPERATURE_LOWER_THRESHOLD to give a wider dynamic range for gradual fan speed scaling.
4. If neither adjustment helps, it may be time to replace your thermal paste.

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Contributing

Contributions are what make the open source community such an amazing place to learn, inspire, and create. Any contributions you make are greatly appreciated.

If you have a suggestion that would make this better, please fork the repo and create a pull request. You can also simply open an issue with the tag "enhancement". Don't forget to give the project a star! Thanks again!

1. Fork the Project
2. Create your Feature Branch (git checkout -b feature/AmazingFeature)
3. Commit your Changes (git commit -m 'Add some AmazingFeature')
4. Push to the Branch (git push origin feature/AmazingFeature)
5. Open a Pull Request

To test locally, use either :

docker build -t jeffsnyder0/dell_idrac_fan_controller:dev .
docker run -d ...

or run directly without Docker:

export IDRAC_HOST=<iDRAC IP address>
export IDRAC_USERNAME=<iDRAC username>
export IDRAC_PASSWORD=<iDRAC password>
export FAN_SPEED_MIN=5
export FAN_SPEED_MAX=50
export CPU_TEMPERATURE_LOWER_THRESHOLD=45
export CPU_TEMPERATURE_UPPER_THRESHOLD=75
export CHECK_INTERVAL=60
export ENABLE_DELL_CONTROL_ON_STARTUP=false
export DISABLE_THIRD_PARTY_PCIE_CARD_DELL_DEFAULT_COOLING_RESPONSE=false
export KEEP_THIRD_PARTY_PCIE_CARD_COOLING_RESPONSE_STATE_ON_EXIT=false

chmod +x Dell_iDRAC_fan_controller.sh
./Dell_iDRAC_fan_controller.sh

To run the test suite (no iDRAC connection required):

bash tests/run_tests.sh

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License

Shield:

This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. The full license description can be read here.

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