fix: hardware-verified corrections from live BC-250 audit

Key fixes:
- nct6687 for fan control (not nct6683 which is read-only)
- GPU is card1 not card0 in all sysfs paths
- Fan on pwm2/fan2 (Pump Fan header), not pwm1
- Vulkan 1.4.328 (not 1.3), Mesa 25.3.6 (not 25.2.4)
- cpupower doesn't work on BC-250 (removed recommendations)
- pp_dmu_clock -> pp_dpm_mclk
- ACPI fix marked as optional/experimental (not essential)
- amdgpu.sg_display=0 only needed for kernels < 6.10
- GPU voltage range 700-1129 mV (from OD_RANGE)
- Added CoolerControl installation instructions
- Expanded sensors.md with proper nct6687 setup guide

docs/troubleshooting/boot.md

@@ -760,7 +760,7 @@ xrandr --listproviders
 
 # DRM devices
 ls -la /sys/class/drm/
-# Should show card0, card0-DP-1
+# Should show card1, card1-DP-1
 
 # Current display mode
 xrandr

docs/troubleshooting/display.md

@@ -505,7 +505,7 @@ xrandr
 
 # Check DRM
 ls /sys/class/drm/
-# Should show card0, card0-DP-1, etc.
+# Should show card1, card1-DP-1, etc.
 ```
 
 ### Check GPU Initialization

docs/troubleshooting/performance.md

@@ -14,7 +14,7 @@ sensors
 
 # Check GPU utilization and frequency
 watch -n 1 cat /sys/devices/pci0000:00/0000:00:08.1/0000:01:00.0/gpu_busy_percent
-watch -n 1 cat /sys/class/drm/card0/device/pp_dmu_clock
+watch -n 1 cat /sys/class/drm/card1/device/pp_dpm_mclk
 
 # Check if GPU driver is loaded
 lspci -k | grep -A 3 VGA
@@ -147,7 +147,7 @@ Apply to kernel source and recompile, or use a tool like `dkms` or CachyOS kerne
 
 **Verification:**
 ```bash
-cat /sys/class/drm/card0/device/pp_od_clk_voltage
+cat /sys/class/drm/card1/device/pp_od_clk_voltage
 # Should show range up to 2300MHz or higher
 ```
 
@@ -229,7 +229,7 @@ dmesg | grep amdgpu
 
 Common fix - ensure these kernel parameters are set (and `nomodeset` is removed):
 ```bash
-# Edit /etc/default/grub
+# Edit /etc/default/grub (sg_display=0 only needed for kernels < 6.10)
 GRUB_CMDLINE_LINUX_DEFAULT="amdgpu.sg_display=0"
 
 # Regenerate grub config
@@ -662,7 +662,7 @@ Use this checklist to verify your system is properly configured:
 **Quick test:**
 ```bash
 # This should show GPU scaling dynamically
-watch -n 0.5 'cat /sys/class/drm/card0/device/pp_dmu_clock && cat /sys/devices/pci0000:00/0000:00:08.1/0000:01:00.0/gpu_busy_percent'
+watch -n 0.5 'cat /sys/class/drm/card1/device/pp_dpm_mclk && cat /sys/devices/pci0000:00/0000:00:08.1/0000:01:00.0/gpu_busy_percent'
 
 # Run a game or benchmark
 # Frequency should scale from ~1000MHz idle to 2000+MHz under load

docs/troubleshooting/stability.md

@@ -648,7 +648,7 @@ watch -n 1 sensors
 
 **Terminal 2 - Frequencies and voltages**:
 ```bash
-watch -n 1 'cat /sys/class/drm/card0/device/pp_od_clk_voltage'
+watch -n 1 'cat /sys/class/drm/card1/device/pp_od_clk_voltage'
 ```
 
 **Terminal 3 - Memory**: