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Windows supports RAM/CPU detection and NVIDIA GPU detection via nvidia-smi.

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GPU Detection

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NVIDIA GPUs

llmfit detects NVIDIA GPUs via two methods:

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1. nvidia-smi (Primary)

nvidia-smi --query-gpu=memory.total,name --format=csv,noheader,nounits
Requirements:
  • NVIDIA drivers installed
  • nvidia-smi.exe in PATH (usually C:\Program Files\NVIDIA Corporation\NVSMI\)
Multi-GPU Support:
  • Aggregates same-model GPUs (e.g., 2x RTX 4090 → count=2, per-card VRAM=24GB)
  • Total VRAM = per-card VRAM × count

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2. WMI (Windows Management Instrumentation)

Fallback method when nvidia-smi is unavailable or for non-NVIDIA GPUs: 
# PowerShell (primary)
Get-CimInstance Win32_VideoController | Select-Object Name,AdapterRAM

# wmic (legacy fallback)
wmic path win32_VideoController get Name,AdapterRAM /format:csv
Detected GPUs:
  • NVIDIA (GeForce, RTX, Quadro, Tesla) → CUDA backend
  • AMD (Radeon, RX) → Vulkan backend
  • Intel (Arc, Iris) → SYCL backend
Filtered entries:
  • Microsoft Basic Display Adapter
  • Virtual/Remote display adapters
VRAM Limitations: WMI AdapterRAM is a 32-bit field capped at ~4 GB. For GPUs with >4 GB VRAM, llmfit estimates from GPU name: 
if vram_gb < 0.1 || (vram_gb <= 4.1 && estimate_vram_from_name(name) > 4.1) {
    vram_gb = estimate_vram_from_name(name);
}

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Installation Methods

scoop install llmfit
If Scoop is not installed: 
# Install Scoop
Set-ExecutionPolicy -ExecutionPolicy RemoteSigned -Scope CurrentUser
Invoke-RestMethod -Uri https://get.scoop.sh | Invoke-Expression

# Install llmfit
scoop install llmfit

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From Source

Prerequisites: 
git clone https://github.com/AlexsJones/llmfit.git
cd llmfit
cargo build --release

# Copy binary to PATH
copy target\release\llmfit.exe C:\Windows\System32\
# or add target\release to PATH

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Binary Download

Download the latest Windows binary from GitHub Releases:
  1. Download llmfit-windows-x64.zip
  2. Extract llmfit.exe
  3. Move to a directory in PATH (e.g., C:\Program Files\llmfit\)
  4. Add to PATH via System Properties → Environment Variables

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WSL (Windows Subsystem for Linux)

llmfit can run natively on Windows or inside WSL. Each has trade-offs:

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Running in WSL2

Advantages:
  • Native Linux environment
  • Better support for ROCm (AMD) if needed
  • Consistent with Linux instructions
Requirements: Installation: 
# Inside WSL2
curl -fsSL https://llmfit.axjns.dev/install.sh | sh
GPU Detection in WSL: llmfit detects WSL via: 
echo $WSL_DISTRO_NAME
cat /proc/version | grep -i microsoft
NVIDIA GPUs work via nvidia-smi in WSL2: 
nvidia-smi
# Should show GPU if CUDA drivers are installed
Known Limitations:
  • AMD ROCm not officially supported in WSL
  • Intel Arc support limited in WSL

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Running Natively on Windows

Advantages:
  • Direct GPU access (no virtualization overhead)
  • Better NVIDIA GPU support
  • WMI fallback for non-NVIDIA GPUs
Recommendation: Use native Windows installation for best GPU detection.

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Troubleshooting

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GPU Not Detected

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NVIDIA GPU

  1. Check if nvidia-smi works: 
    nvidia-smi
  2. If nvidia-smi not found: 
    # Check PATH
$env:PATH -split ';' | Select-String -Pattern 'NVIDIA'

# Add to PATH if missing
$env:PATH += ";C:\Program Files\NVIDIA Corporation\NVSMI"
  3. Reinstall NVIDIA drivers:
  4. Check WMI fallback: 
    Get-CimInstance Win32_VideoController | Select-Object Name,AdapterRAM
  5. Manual override: 
    llmfit --memory=24G system

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AMD/Intel GPU

AMD and Intel GPUs rely on WMI detection: 
Get-CimInstance Win32_VideoController | Select-Object Name,AdapterRAM,DriverVersion
Expected output: 
Name                        AdapterRAM  DriverVersion
----                        ----------  -------------
AMD Radeon RX 7900 XTX     25769803776  31.0.24001.18012
If AdapterRAM shows low value (< 4 GB) for high-VRAM GPU, llmfit estimates from name.

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VRAM Shows Incorrect Value

WMI 32-bit limitation: WMI reports wrong VRAM for GPUs with >4 GB: 
# Check raw value
(Get-CimInstance Win32_VideoController).AdapterRAM
llmfit automatically falls back to name-based estimation. If incorrect, use manual override: 
llmfit --memory=16G

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nvidia-smi Works But llmfit Doesn’t Detect GPU

PATH issue: 
# Check if nvidia-smi is in PATH
Get-Command nvidia-smi

# If not found, add to PATH
$env:PATH += ";C:\Program Files\NVIDIA Corporation\NVSMI"

# Make permanent via System Properties → Environment Variables
Command execution issue: llmfit spawns nvidia-smi as a subprocess. Check for permission issues: 
# Run llmfit as Administrator
Start-Process powershell -Verb RunAs
llmfit system

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WSL-Specific Issues

nvidia-smi not working in WSL:
  1. Install CUDA drivers for WSL:
  2. Restart WSL: 
    wsl --shutdown
wsl
  3. Verify GPU access: 
    nvidia-smi
WSL not detected: llmfit checks for WSL via environment variables: 
echo $WSL_DISTRO_NAME
echo $WSL_INTEROP
cat /proc/version | grep -i microsoft
If none exist, WSL detection fails (non-critical, only affects logging).

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Performance Issues

High VRAM usage: Check VRAM usage via Task Manager:
  1. Task Manager → Performance → GPU
  2. Watch “Dedicated GPU memory” usage
If near capacity:
  • Close GPU-intensive apps (browsers, games)
  • Use --max-context to limit context length: 
    llmfit --max-context 4096
Slow inference estimates: llmfit uses GPU memory bandwidth for speed estimation. Check GPU model detection: 
llmfit system
# GPU: NVIDIA GeForce RTX 4090 (24.00 GB VRAM, CUDA)
If GPU model is wrong or generic (“NVIDIA GPU”), speed estimates may be inaccurate.

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Known Limitations

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AMD GPU Support

  • No ROCm on Windows: AMD GPUs use Vulkan backend (slower than ROCm on Linux)
  • VRAM detection: Relies on WMI (may be inaccurate for >4 GB GPUs)
  • Workaround: Use manual override for accurate VRAM: 
    llmfit --memory=24G  # For RX 7900 XTX

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Intel Arc Support

  • Limited detection: Relies on WMI
  • SYCL backend: Requires Intel oneAPI runtime (not auto-detected)
  • Recommendation: Use NVIDIA GPU or run in WSL2 for better Intel Arc support

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Multi-GPU Limitations

  • Different vendors: llmfit uses the GPU with most VRAM as primary
  • Mixed NVIDIA + AMD: Only NVIDIA detected via nvidia-smi, AMD via WMI
  • Check detection: 
    llmfit system
# Should list all detected GPUs

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Next Steps

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