amd-bc250-docs/docs/system/sensors.md

Sensors and Monitoring

Guide to monitoring temperatures, fan speeds, voltages, and performance metrics on the BC-250.

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Overview

The BC-250 includes multiple hardware monitoring components:

• Nuvoton NCT6686D SuperIO chip - Motherboard sensors (temperatures, voltages, fan speeds)
  • For read-only monitoring: use the in-kernel nct6683 driver (with force=true)
  • For read+write PWM fan control: use the out-of-tree nct6687 driver (Fred78290/nct6687d) with force=true
• AMD GPU sensors - GPU temperature, voltage, power consumption
• k10temp - CPU temperature monitoring
• NVMe sensors - M.2 drive temperature

Proper monitoring is essential to ensure your BC-250 stays within safe operating temperatures (70-85°C under load) and to diagnose cooling or power issues.

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SuperIO Driver Setup

About the SuperIO Chip

The BC-250 uses a Nuvoton NCT6686D Super I/O chip for hardware monitoring. There are two Linux driver options:

• nct6683 (in-kernel) — Read-only access to sensors (temperatures, voltages, fan speeds). Cannot control fan PWM.
• nct6687 (out-of-tree, Fred78290/nct6687d) — Full read+write access including PWM fan control. Required if you want software fan control.

Both require force=true because the chip isn't auto-detected. Regardless of which module is loaded, sensors will report as nct6686-isa-0a20.

The chip provides:

• Multiple temperature sensors (CPU, System, VRM MOS, and more)
• Voltage rails monitoring (+12V, +5V, +3.3V, CPU Soc, CPU Vcore, etc.)
• Fan speed monitoring (up to 8 fan headers)
• PWM fan control (only with nct6687 module)

Loading the Sensor Module

By default, Linux may not automatically load the driver for this chip. You need to manually enable it.

Option A: Read-Only Sensors (nct6683)

Use this if you only need temperature/voltage/fan speed monitoring without PWM fan control.

Step 1: Test if the module loads correctly:

sudo modprobe nct6683 force=true

Step 2: Make it permanent:

echo 'options nct6683 force=true' | sudo tee /etc/modprobe.d/sensors.conf
echo 'nct6683' | sudo tee /etc/modules-load.d/99-sensors.conf

Option B: Full PWM Fan Control (nct6687 — Recommended)

Use this if you want software fan speed control (CoolerControl, manual PWM, etc.).

Step 1: Build and install the nct6687 module:

git clone https://github.com/Fred78290/nct6687d.git
cd nct6687d
make
sudo make install

Step 2: Configure modprobe to use nct6687 and blacklist nct6683:

# Blacklist nct6683 (conflicts with nct6687)
echo 'blacklist nct6683' | sudo tee /etc/modprobe.d/sensors.conf
echo 'options nct6687 force=true' | sudo tee -a /etc/modprobe.d/sensors.conf

# Load nct6687 on boot
echo 'nct6687' | sudo tee /etc/modules-load.d/99-sensors.conf

!!!warning "Choose One Module" Do not load both nct6683 and nct6687 simultaneously — they conflict. Blacklist whichever you're not using.

Regenerate Initramfs

On Fedora/Bazzite:

sudo dracut --force

On Arch/Manjaro:

sudo mkinitcpio -P

On Debian/Ubuntu:

sudo update-initramfs -u

Reboot for changes to take effect:

sudo reboot

!!!info "PWM Values Reset on Reboot" The nct6687 module does not persist PWM values across reboots. You'll need CoolerControl, a systemd service, or a udev rule to set your desired fan speed at boot.

Immutable / Atomic Distros (Bazzite, Silverblue, Fedora CoreOS)

On atomic/immutable distros (Bazzite, Silverblue, Fedora CoreOS, Kinoite) the sudo make install step above won't work. The build succeeds, but the copy fails:

cp: cannot create '/lib/modules/.../nct6687.ko': Read-only file system

/usr/lib/modules is read-only on an ostree image, so the module compiles fine but can never be copied into the kernel tree. That's also why modprobe nct6687 reports the module as missing afterwards. There are two working paths, depending on which kernel you run.

Stock Bazzite kernel: Bazzite ships the nct6687d driver as an akmod from ublue-os/akmods. It was dropped on 2025-01-31 and restored in the 41.20250314 stable release, so on an up-to-date stock kernel you don't build anything, just load it:

sudo modprobe nct6687 force=true

Custom BC-250 kernel: Prebuilt akmods are tied to the stock kernel ABI, so a custom kernel (any non-stock suffix such as -ogc) has no matching akmod and modprobe finds nothing. Build the module against the running kernel as shown above, then load the built .ko directly instead of installing it:

cd nct6687d
sudo insmod ./"$(uname -r)"/nct6687.ko force=1

Confirm it bound with lsmod | grep nct6687 and sensors.

insmod isn't persistent: it doesn't survive a reboot, and the module has to be rebuilt after every kernel update because the path is tied to uname -r. To persist it, keep the built .ko somewhere writable under /var and load it at boot with a systemd oneshot service:

# /etc/systemd/system/nct6687-load.service
[Unit]
Description=Load nct6687 SuperIO sensor module
After=multi-user.target

[Service]
Type=oneshot
ExecStart=/usr/sbin/insmod /var/lib/nct6687/nct6687.ko force=1
RemainAfterExit=yes

[Install]
WantedBy=multi-user.target

Then copy the module into place and enable the service:

sudo mkdir -p /var/lib/nct6687
sudo cp ./"$(uname -r)"/nct6687.ko /var/lib/nct6687/
sudo systemctl enable nct6687-load.service

Remember to rebuild and recopy the .ko after each kernel update. If you'd rather not wire this up by hand, the NeOdYmS/bazzite-bc250-toolkit project automates this nct6683 to nct6687 switch on BC-250 Bazzite.

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Using lm-sensors

Installation

Fedora/Bazzite:

sudo dnf install lm_sensors

Arch/Manjaro:

sudo pacman -S lm_sensors

Debian/Ubuntu:

sudo apt install lm-sensors

Detecting Sensors

Run the detection utility (answer YES to all prompts):

sudo sensors-detect

This will scan for all available sensors and configure them automatically.

Reading Sensor Data

View all sensor readings:

sensors

Expected Output

The output varies depending on which Super I/O module you loaded.

With nct6687 module (recommended — enables PWM fan control):

amdgpu-pci-0100
Adapter: PCI adapter
vddgfx:      699.00 mV
vddnb:         1.10 V
edge:         +46.0°C
PPT:          38.01 W  (avg =  40.25 W)

nvme-pci-0300
Adapter: PCI adapter
Composite:    +38.9°C  (low  =  -0.1°C, high = +82.8°C)
                       (crit = +84.8°C)
Sensor 1:     +38.9°C  (low  = -273.1°C, high = +65261.8°C)

k10temp-pci-00c3
Adapter: PCI adapter
Tctl:         +47.9°C

nct6686-isa-0a20
Adapter: ISA adapter
+12V:            0.00 V  (min =  +0.00 V, max =  +0.00 V)
+5V:             0.00 V  (min =  +0.00 V, max =  +0.00 V)
+3.3V:           3.36 V  (min =  +0.00 V, max =  +3.36 V)
CPU Soc:         0.00 V  (min =  +0.00 V, max =  +0.00 V)
CPU Vcore:       0.00 V  (min =  +0.00 V, max =  +0.00 V)
CPU Fan:          0 RPM  (min =    0 RPM, max =    0 RPM)
Pump Fan:      1907 RPM  (min = 1866 RPM, max = 1907 RPM)
System Fan #1:    0 RPM  (min =    0 RPM, max =    0 RPM)
...
CPU:            +47.0°C  (low  = +35.0°C, high = +47.0°C)
System:         +42.5°C  (low  = +20.0°C, high = +42.5°C)
VRM MOS:        +42.0°C  (low  = +20.0°C, high = +42.0°C)

With nct6683 module (read-only, no fan control):

nct6686-isa-0a20
Adapter: ISA adapter
VIN0:             832.00 mV (min =  +0.00 V, max =  +0.00 V)
...
fan1:                0 RPM  (min =    0 RPM)
fan2:             1372 RPM  (min =    0 RPM)
...
AMD TSI Addr 98h:  +63.0°C  ...  sensor = AMD AMDSI
Thermistor 14:     +57.5°C  ...  sensor = thermistor
Thermistor 15:     +57.0°C  ...  sensor = thermistor

!!!info "Sensor Names Differ By Module" Both modules report as nct6686-isa-0a20, but the nct6687 module provides named labels (CPU Fan, Pump Fan, CPU Soc, etc.) while nct6683 shows generic names (VIN0, fan1, Thermistor 14, etc.).

Understanding the Sensors

GPU Sensors (amdgpu-pci-0100):

• vddgfx - GPU core voltage
• vddnb - Northbridge/memory voltage
• edge - GPU edge temperature (primary GPU temp)
• PPT - Package Power Tracking (GPU power consumption in watts)

CPU Sensors (k10temp-pci-00c3):

• Tctl - CPU temperature (Zen 2 control temperature)

SuperIO Sensors (nct6686-isa-0a20):

With nct6687 module:

• +12V, +5V, +3.3V, CPU Soc, CPU Vcore etc. - Named voltage rails
• CPU Fan, Pump Fan, System Fan #1-6 - Named fan speed monitoring (RPM), up to 8 channels
• CPU, System, VRM MOS - Named temperature sensors

With nct6683 module:

• VIN0-VIN16 - Voltage rails (generic names)
• fan1-fan5 - Fan speed monitoring (RPM)
• AMD TSI Addr 98h - AMD Temperature Sensor Interface (CPU temp)
• Thermistor 14/15 - Board temperature sensors

Watch Sensors in Real-Time

Monitor sensor changes continuously:

watch -n 1 sensors

This updates every second. Press Ctrl+C to exit.

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GPU Temperature Monitoring

Using AMDGPU Sysfs

Read GPU temperature directly:

cat /sys/class/drm/card0/device/hwmon/hwmon*/temp1_input

This returns temperature in millidegrees Celsius (e.g., 63000 = 63°C)

Convert to Celsius:

awk '{print $1/1000 "°C"}' /sys/class/drm/card0/device/hwmon/hwmon*/temp1_input

GPU Power Consumption

Read current GPU power draw:

cat /sys/class/drm/card0/device/hwmon/hwmon*/power1_average

Returns power in microwatts. Convert to watts:

awk '{print $1/1000000 "W"}' /sys/class/drm/card0/device/hwmon/hwmon*/power1_average

GPU Clock Speeds

Check current GPU frequency:

cat /sys/class/drm/card0/device/pp_dpm_sclk

Example output:

0: 350Mhz
1: 1000Mhz *
2: 2000Mhz

The asterisk (*) indicates the current active clock speed.

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Fan Speed Monitoring and Control

Viewing Fan Speeds

From sensors output, look for the nct6686-isa-0a20 section:

sensors | grep -A 5 "fan"

Fan Headers on BC-250

The board has two physical fan headers: J1 (primary) and J4003 (secondary).

The Super I/O chip exposes up to 8 fan channels in software (fan1-fan8), but only the connected headers will show RPM readings:

• The main cooling fan typically reads as Pump Fan (fan2 in nct6687 output, or fan2 in nct6683 output)
• Other channels show 0 RPM if not connected

BIOS Fan Control Settings

The BC-250 BIOS has three fan control modes:

1. Default - Tries to keep board at maximum safe temperature with minimum fan speed (NOT RECOMMENDED - runs too hot)
2. Full Speed - Fans run at 100% constantly (recommended for testing and maximum cooling)
3. Customize - Set custom temperature/fan speed curves in BIOS

Recommendation: Use "Full Speed" mode for initial testing and gaming. Once stable, you can use software fan control (CoolerControl) for quieter operation.

Manual Fan Control via PWM

!!!warning "Requires nct6687 Module" PWM fan control requires the nct6687 module. The in-kernel nct6683 module provides read-only access and cannot set PWM values.

Check available PWM controls:

ls /sys/class/hwmon/hwmon*/pwm*

Set fan speed manually (value 0-255, where 255 = 100%):

# Find the hwmon for nct6686
HWMON=$(grep -l nct6686 /sys/class/hwmon/hwmon*/name | head -1 | xargs dirname)

# Set PWM (0=off, 127=50%, 255=100%)
echo 80 | sudo tee $HWMON/pwm2

!!!info "PWM Resets on Reboot" PWM values set manually are not persistent across reboots. Use CoolerControl or a systemd service to set fan speed at boot.

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CoolerControl - GUI for Sensor Monitoring and Fan Curves

CoolerControl is a GUI application that provides:

• Real-time sensor monitoring
• Custom fan curves based on any temperature sensor
• Historical temperature graphs
• Fan speed control

Installation on Bazzite

Bazzite has a built-in recipe for CoolerControl:

ujust install-coolercontrol

This will:

1. Enable the Terra repository
2. Install liquidctl and coolercontrol
3. Require a reboot to apply

After reboot, start CoolerControl:

coolercontrol

Installation on Fedora

Enable the Terra repository:

sudo dnf copr enable copr.fedorainfracloud.org/terra

Install CoolerControl:

sudo dnf install liquidctl coolercontrol

Installation on Arch/Manjaro

Install from AUR:

yay -S coolercontrol

Or:

paru -S coolercontrol

Using CoolerControl

1. Launch CoolerControl from your application menu or terminal
2. You'll see all detected sensors and fans
3. Click on a fan to create a custom curve
4. Select a temperature sensor to base the curve on (e.g., GPU edge temp)
5. Drag curve points to set fan speed at different temperatures

Example fan curve:

• 40°C: 30% fan speed
• 60°C: 50% fan speed
• 70°C: 75% fan speed
• 80°C: 100% fan speed

Checking Frequency and Temperature with Governor

From Discord community recommendations:

Desktop mode:

# Use CoolerControl (installed with ujust on Bazzite)
coolercontrol

Game mode (Steam Deck UI):

• Enable Steam overlay performance monitoring in Quick Settings

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Other Monitoring Tools

nvtop - GPU Activity Monitor

nvtop is like htop but for GPUs. It shows GPU utilization, VRAM usage, temperature, and power consumption in a terminal UI.

Installation:

Fedora/Bazzite:

sudo dnf install nvtop

Arch/Manjaro:

sudo pacman -S nvtop

Debian/Ubuntu:

sudo apt install nvtop

Usage:

nvtop

Press q to quit.

radeontop - AMD GPU Monitor

Alternative GPU monitoring tool specifically for AMD GPUs.

Installation:

Fedora/Bazzite:

sudo dnf install radeontop

Arch/Manjaro:

sudo pacman -S radeontop

Debian/Ubuntu:

sudo apt install radeontop

Usage:

radeontop

Press q to quit.

MangoHud - In-Game Overlay

MangoHud provides an in-game overlay showing FPS, GPU/CPU temps, usage, and more.

Installation:

Fedora/Bazzite:

sudo dnf install mangohud

Arch/Manjaro:

sudo pacman -S mangohud

Debian/Ubuntu:

sudo apt install mangohud

Usage:

Launch games with MangoHud:

mangohud %command%

For Steam games, add to launch options:

mangohud %command%

Configuration:

Create ~/.config/MangoHud/MangoHud.conf:

fps_limit=60
vsync=0
gpu_temp
cpu_temp
gpu_power
cpu_power
ram
vram
fps
frametime=0
frame_timing=1
position=top-left
font_size=24

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Temperature Thresholds and Safe Operating Ranges

Normal Operating Temperatures

Idle (Desktop/Light Use):

• GPU: 45-55°C
• CPU: 45-55°C
• Power: 50-70W

Gaming/Heavy Load:

• GPU: 70-85°C
• CPU: 65-80°C
• Power: 150-235W (235W max during Cyberpunk with ray tracing)

Maximum Safe Temperatures

• GPU edge temp: 85°C maximum recommended (can briefly spike to 90°C)
• CPU (Tctl): 90°C maximum
• NVMe SSD: 80°C maximum (critical at 81.8°C per spec)

Temperature Warning Signs

If you see these symptoms, your cooling is insufficient:

• GPU consistently above 85°C during gaming
• Sudden FPS drops or stuttering (thermal throttling)
• System crashes under load
• GPU governor reducing frequency to manage heat

Improving Cooling

If temperatures are too high:

1. Check fan speeds - Ensure fans are running at adequate RPM
2. Verify thermal paste - Reapply if paste is old or dried
3. Increase fan speed - Use BIOS "Full Speed" mode or CoolerControl
4. Improve airflow - Add more fans or cut heatsink fins for better air penetration
5. Check dust - Clean dust from heatsink fins
6. Verify thermal pads - Ensure good contact on GDDR6 memory chips

Community Cooling Data

From Discord testing:

• Arctic P12 Max with cut fins: 70-85°C gaming, 86°C benchmarks
• Noctua NF-A12x25 with cut fins: 65-80°C gaming
• Stock heatsink with fan shroud: 80-90°C gaming (thermal limits reached)
• Wraith Stealth coolers with thermal putty: ~70°C mining/LLM workloads at 180W

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Troubleshooting Sensor Issues

Sensors Command Shows No Output

Problem: Running sensors shows nothing or very limited data.

Solutions:

1. Run sensor detection:

   sudo sensors-detect
   

2. Ensure NCT6683 module is loaded:

   sudo modprobe nct6683 force=true
   

3. Check if modules are loaded:

   lsmod | grep -E "nct6683|k10temp|amdgpu"
   

4. Verify lm-sensors is installed:

   sensors --version
   

Sensor Module Won't Load

Problem: modprobe nct6683 force=true or modprobe nct6687 force=true fails.

Solutions:

1. Check kernel version (needs 6.11+):

   uname -r
   

2. Check dmesg for errors:

   dmesg | grep -i nct
   

3. Ensure the modules are not conflicting — only load one at a time:

   # Check what's loaded
   lsmod | grep nct
   
   # If nct6683 is loaded but you want nct6687:
   sudo rmmod nct6683
   sudo modprobe nct6687 force=true
   

4. For nct6687, you may need to build from source if it's not packaged for your distro:

   git clone https://github.com/Fred78290/nct6687d.git
   cd nct6687d && make && sudo make install
   sudo modprobe nct6687 force=true
   

   On atomic/immutable distros make install fails because the kernel tree is read-only. See the Immutable / Atomic Distros subsection above.

!!!info "nct6683 vs nct6687" nct6683 is read-only (temperature, voltage, fan speed monitoring). nct6687 provides full read+write access including PWM fan control. For fan curves and manual speed control, you need nct6687.

GPU Temperature Not Showing

Problem: No GPU temperature in sensors output.

Solutions:

1. Check if amdgpu driver is loaded:

   lsmod | grep amdgpu
   

2. Verify GPU is detected:

   lspci | grep VGA
   

3. Check amdgpu sysfs directly:

   cat /sys/class/drm/card0/device/hwmon/hwmon*/temp1_input
   

4. Ensure Mesa 25.1+ is installed:

   glxinfo | grep "OpenGL version"
   

Fan Speeds Show 0 RPM

Problem: All fans show 0 RPM even though fans are spinning.

Possible causes:

1. Fan not connected to monitored header - BC-250 usually only uses fan2 header
2. 3-pin fan on PWM header - Some fans don't report speed
3. Fan splitter - May not pass tachometer signal
4. BIOS fan setting - Try changing fan mode in BIOS

Verification:

If you can hear/feel the fan spinning, it's working even if sensors show 0 RPM. Use GPU temperature as confirmation of cooling effectiveness.

Power Consumption Seems Wrong

Problem: sensors shows very low or zero power consumption.

Solution:

1. Power readings update slowly - wait 10-30 seconds
2. Use a Kill-A-Watt or smart plug for accurate wall power measurement
3. GPU power from sensors only shows GPU chip power, not total system power
4. Total system power = GPU + CPU + RAM + board + PSU inefficiency

Example:

• GPU PPT: 150W
• Total system power at wall: 180-200W

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Advanced: Monitoring Scripts

Temperature Logging Script

Save as ~/monitor-temps.sh:

#!/bin/bash

# BC-250 Temperature Monitor
# Logs GPU temp, CPU temp, and power to file

LOGFILE="$HOME/bc250-temps.log"

echo "Timestamp,GPU_Temp,CPU_Temp,GPU_Power" > "$LOGFILE"

while true; do
    TIMESTAMP=$(date +%s)
    GPU_TEMP=$(cat /sys/class/drm/card0/device/hwmon/hwmon*/temp1_input 2>/dev/null | awk '{print $1/1000}')
    CPU_TEMP=$(sensors k10temp-pci-00c3 -u 2>/dev/null | grep temp1_input | awk '{print $2}')
    GPU_POWER=$(cat /sys/class/drm/card0/device/hwmon/hwmon*/power1_average 2>/dev/null | awk '{print $1/1000000}')

    echo "$TIMESTAMP,$GPU_TEMP,$CPU_TEMP,$GPU_POWER" >> "$LOGFILE"
    sleep 5
done

Make executable:

chmod +x ~/monitor-temps.sh

Run:

~/monitor-temps.sh

Temperature Alert Script

Save as ~/temp-alert.sh:

#!/bin/bash

# Alert if GPU temp exceeds threshold
THRESHOLD=85

while true; do
    GPU_TEMP=$(cat /sys/class/drm/card0/device/hwmon/hwmon*/temp1_input 2>/dev/null | awk '{print $1/1000}')

    if (( $(echo "$GPU_TEMP > $THRESHOLD" | bc -l) )); then
        notify-send -u critical "BC-250 Temperature Alert" "GPU temp: ${GPU_TEMP}°C (threshold: ${THRESHOLD}°C)"
    fi

    sleep 10
done

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Quick Reference

Essential Commands

# View all sensors
sensors

# Watch sensors in real-time
watch -n 1 sensors

# GPU temperature only
cat /sys/class/drm/card0/device/hwmon/hwmon*/temp1_input | awk '{print $1/1000 "°C"}'

# GPU power consumption
cat /sys/class/drm/card0/device/hwmon/hwmon*/power1_average | awk '{print $1/1000000 "W"}'

# GPU clock speed
cat /sys/class/drm/card0/device/pp_dpm_sclk

# Launch nvtop
nvtop

# Launch radeontop
radeontop

Temperature Targets

Condition	GPU Temp	CPU Temp	Power Draw
Idle	45-55°C	45-55°C	50-70W
Light Gaming	60-75°C	55-70°C	100-150W
Heavy Gaming	70-85°C	65-80°C	150-200W
Stress Test	80-86°C	75-85°C	200-235W

Cooling Solutions Performance

Setup	Idle Temp	Load Temp	Notes
Arctic P12 Max (cut fins)	49°C	70-86°C	Best performance
Noctua NF-A12x25 (cut fins)	47-52°C	65-80°C	Quieter, excellent cooling
Single 120mm (cut fins)	55°C	80-90°C	Adequate for most games
Stock with shroud	60°C	85-90°C	Borderline, may throttle

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Related Documentation

• GPU Governor - Configure GPU frequency scaling and power management
• Performance Tuning - Optimize system performance
• Hardware Overview - BC-250 specifications and cooling requirements
• Troubleshooting - Solve thermal and stability issues

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Last Updated: March 18, 2026