For cachyOS Deckify 40CU unlock
BC-250 40CU Unlock Guide for CachyOS Deckify (Recommended Setup)
This guide walks through the exact process to:
unlock all 40 CUs on the AMD BC-250
use the CachyOS Kernel Manager GUI
correctly enable the runtime patch
configure the Cyan Skillfish governor
cap clocks safely at 1500 MHz
This guide is specifically for:
CachyOS Deckify
linux-cachyos-deckify
BC-250 / Cyan Skillfish systems
This is the setup that successfully worked with the newer BC250 fixes included in the Deckify kernel.
1. Verify You’re Running the Deckify Kernel
Open terminal:
uname -r
You should see something like:
7.x.x-cachyos-deckify
If not, install it:
sudo pacman -S linux-cachyos-deckify linux-cachyos-deckify-headers
Reboot if necessary.
2. Install CachyOS Kernel Manager
If not already installed:
sudo pacman -S cachyos-kernel-manager
Launch it from:
application menu → “CachyOS Kernel Manager”
or:
cachyos-kernel-manager
3. Download the BC-250 Patch
Open terminal:
mkdir -p ~/bc250-patch
cd ~/bc250-patch
curl -LO https://raw.githubusercontent.com/duggasco/bc250-40cu-unlock/main/patch/bc250-40cu-amdgpu.patch
You should now have:
~/bc250-patch/bc250-40cu-amdgpu.patch
4. Build a Custom Patched Kernel
Inside CachyOS Kernel Manager:
Click:
Configure
Set:
Package Name:
linux-bc250
Base Kernel:
linux-cachyos-deckify
This is important:
Deckify includes newer BC250-related fixes
better RDNA2/APU handling
newer AMDGPU behavior
5. Add the BC250 Patch
Inside Kernel Manager:
Find:
Kernel Patches Management
Click:
Add Local Patch
Select:
~/bc250-patch/bc250-40cu-amdgpu.patch
The patch should now appear in the patch list.
6. Build the Kernel
Click:
Build Kernel
Wait for the build to finish.
This can take:
20–90 minutes depending on CPU
When prompted, allow installation.
7. Reboot Into the New Kernel
Reboot.
At the boot menu select:
linux-bc250
Verify:
uname -r
You should now see your custom kernel name.
8. ENABLE THE PATCH (MOST IMPORTANT STEP)
The kernel patch alone does NOT activate 40CU mode.
You MUST enable the runtime parameter.
Create the config:
sudo nano /etc/modprobe.d/bc250-40cu.conf
Add:
options amdgpu bc250_cc_write_mode=3
Save.
9. Rebuild Initramfs
VERY IMPORTANT:
sudo mkinitcpio -P
Without this step, the patch will not activate at boot.
10. Reboot Again
sudo reboot
11. Verify the Patch Is Working
Check:
dmesg | grep bc250-40cu
Expected output:
bc250-40cu-enable: mode=3 ...
Then check CU count:
dmesg | grep active_cu_number
Expected:
active_cu_number 40
You can also run:
RADV_DEBUG=info vulkaninfo --summary 2>&1 | grep num_cu
Expected:
num_cu = 40
12. Install Cyan Skillfish Governor
Install:
yay -S cyan-skillfish-governor-smu
Enable service:
sudo systemctl enable --now cyan-skillfish-governor-smu.service
Verify:
systemctl status cyan-skillfish-governor-smu.service
You want:
active (running)
13. Configure Safe 1500 MHz Profile
Edit config:
sudo nano /etc/cyan-skillfish-governor/config.toml
Set:
[[safe-points]]
frequency = 300
voltage = 700
[[safe-points]]
frequency = 900
voltage = 800
[[safe-points]]
frequency = 1500
voltage = 900
Save.
This keeps:
temps reasonable
power manageable
avoids 2GHz+ thermal runaway
14. Make Sure GPU Is In AUTO Mode
IMPORTANT:
echo auto | sudo tee /sys/class/drm/card0/device/power_dpm_force_performance_level
Do NOT use:
manual
high
with cyan-skillfish-governor.
The governor needs automatic DPM control.
15. Restart the Governor
sudo systemctl restart cyan-skillfish-governor-smu
16. Verify Clock Limits
Watch clocks live:
watch -n 1 cat /sys/class/drm/card0/device/pp_dpm_sclk
Under load, clocks should:
boost normally
cap around 1500 MHz
remain stable
17. Optional Verification Tools
Check CU layout:
./scripts/cu_map.sh
Check Vulkan CU count:
vulkaninfo | grep num_cu
Check temps/power:
watch -n 1 sensors
Expected Results
Typical results at 1500 MHz / 900 mV:
Mode
Performance
Power
Temp
Stock 24 CU
~230 tok/s
~95W
~79C
40 CU unlocked
~370 tok/s
~125W
~83C
Common Problems
Still seeing 24 CU
You forgot:
options amdgpu bc250_cc_write_mode=3
OR forgot:
sudo mkinitcpio -P
No bc250-40cu-enable message in dmesg
The runtime parameter is not loading correctly.
Check:
cat /proc/cmdline
and:
modinfo amdgpu | grep bc250
Clocks exceed 1500 MHz
GPU is still in manual DPM mode.
Fix:
echo auto | sudo tee /sys/class/drm/card0/device/power_dpm_force_performance_level
Governor not working
Check:
systemctl status cyan-skillfish-governor-smu
Kernel build fails
Usually caused by:
patch mismatch
wrong kernel selected
missing headers
Install:
sudo pacman -S linux-cachyos-deckify-headers
Final Notes
The important pieces are:
Component
Purpose
Deckify Kernel
latest BC250 fixes
Kernel Patch
adds 40CU support
bc250_cc_write_mode=3
activates the unlock
Cyan Skillfish Governor
keeps clocks/temps sane
1500 MHz cap
best efficiency/performance balance
Without all three together:
CU unlock may fail
clocks may overheat
performance may be unstable