SYSTEM DETAILS
- CPU: AMD Ryzen 7 5700X
- Motherboard: ASUS Prime B550-Plus
- Kernel:
linux-cachyos-bore-lto - Scaling Driver:
amd-pstate-epp(unable to switch toamd-pstate) - Issue: CPU is capped at 3.6 GHz, even under load, despite boost being “Active.”
- Expected Behavior: CPU should boost up to 4.6 GHz (custom Pstate0) or 4.9 GHz (stock max boost).
BIOS CHANGES MADE
Precision Boost Overdrive (PBO) Settings
- PBO Mode → Set to Advanced
- PBO Limits → Set to Motherboard
- PBO Scalar → Set to 10X
- Max CPU Boost Clock Override → Set to +25 MHz
- Curve Optimizer → Set to Negative
General CPU Performance Settings
- Core Performance Boost → Enabled
- Global C-State Control → Auto (considered disabling if needed)
- APBDIS (APU Boost Disable) → Set to 0 (Ensures boosting is enabled)
- CPPC (Collaborative Power and Performance Control) → Enabled
- CPPC Preferred Cores → Enabled
P-State Configuration
- Pstate0 Frequency → Manually set to 4.6 GHz
- Pstate0 VID (Voltage ID) → Left untouched for safety
- Attempted to unlock
pcdocdisablesetting but couldn’t locate it
LINUX-SIDE CHANGES & TESTS
CPU Frequency Scaling Changes
- Set governor to
performance:
echo "performance" | sudo tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor
- Set min/max CPU frequency:
echo 1800000 | sudo tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_min_freq
echo 4600000 | sudo tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_max_freq
- Installed and configured
cpupower:
sudo pacman -S cpupower
sudo systemctl enable --now cpupower.service
* Verified that `cpupower frequency-info` showed correct limits (1.8 - 4.6 GHz)
---
### **Boost Enabling Attempts**
* **Checked if boost was disabled:**
cat /sys/devices/system/cpu/cpufreq/boost
* **Result:** `0` (boost disabled)
* **Attempted to enable boost manually:**
echo 1 | sudo tee /sys/devices/system/cpu/cpufreq/boost
* **Result:** `Invalid argument` (kernel rejected change)
* **Tried enabling boost via systemd service:**
sudo nano /etc/systemd/system/cpufreq-boost.service
* **Did not work** (boost setting remained `0`).
* **Tried enabling boost via udev rule:**
sudo nano /etc/udev/rules.d/99-cpufreq-boost.rules
* **Did not work** (boost setting remained `0`).
* **Checked if SELinux was enforcing restrictions (`getenforce`)** → **Not applicable on CachyOS**
* **Checked AppArmor logs for potential security blocks** → **No relevant logs found**
---
### **Kernel Parameter Modifications (GRUB)**
* **Added `cpufreq_boost=1` to GRUB:**
sudo nano /etc/default/grub
* Modified:
ini
GRUB_CMDLINE_LINUX_DEFAULT=“nowatchdog nvme_load=YES zswap.enabled=0 splash loglevel=3 sched_bore cpufreq_boost=1”
* **Rebuilt GRUB config and rebooted:**
sudo grub-mkconfig -o /boot/grub/grub.cfg
sudo reboot
* **Result:** Boost setting **still remained `0`**
* **Attempted to force `amd-pstate` over `amd-pstate-epp`:**
echo active | sudo tee /sys/devices/system/cpu/amd_pstate/status
* **Result:** `amd-pstate-epp` remained locked in place
* **Checked scaling driver (still stuck at `amd-pstate-epp`)**
cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_driver
* **Attempted to remove `amd-pstate-epp` and load `acpi_cpufreq`:**
sudo modprobe -r amd_pstate
sudo modprobe acpi_cpufreq
* **Result:** `modprobe: Module amd_pstate not found.`
* **Checked if kernel supported boost (`/boot/config-*`):**
cat /boot/config-$(uname -r) | grep -i cpufreq
* **Result:** Confirmed boost should be supported (`CONFIG_X86_ACPI_CPUFREQ_BOOST=y`)
---
## **🚨 RESULTS & CURRENT STATUS**
### **🔍 What Works:**
* **Governor, min/max frequencies, and boost state are all set correctly.**
* **CPU correctly reports boost as "Active."**
* **Scaling range is correctly set to 1.8 GHz - 4.6 GHz.**
### **❌ What Still Fails:**
* **Stress testing (`stress-ng`) confirms CPU is still stuck at 3.6 GHz.**
* **Boost (`/sys/devices/system/cpu/cpufreq/boost`) remains locked at `0` with no way to force `1`.**
* **`amd-pstate-epp` refuses to switch to `amd-pstate` or `acpi_cpufreq`.**
* **Kernel parameters (`cpufreq_boost=1`) have no effect.**