# Local LLM Server - Build Guide

**Created:** 2026-02-09
**Purpose:** Dedicated local LLM inference server for smart home + general use

---

## Recommended Build: RTX 4090 (Sweet Spot)

| Component | Spec | Est. Cost |
|---|---|---|
| GPU | NVIDIA RTX 4090 24GB | $1,200-1,500 |
| CPU | AMD Ryzen 7 5800X3D | $250 |
| Motherboard | B550 | $120 |
| RAM | 64GB DDR4 (2x32GB) | $120 |
| Storage | 1TB NVMe Gen4 | $80 |
| PSU | 850W Gold | $100 |
| Case | Mid-tower, good airflow | $70 |
| **Total** | | **$1,940-2,240** |

### Why This Build

- 24GB VRAM runs 70B parameter models at 4-bit quantization (7-9 tok/s)
- 30B models at 8-bit quality (20+ tok/s)
- 7-8B models at full speed (30+ tok/s)
- Handles everything from quick voice commands to serious reasoning
- Single GPU keeps complexity low

### Alternative Builds

**Budget (~$580):**
- RTX 3060 12GB (used, $250)
- Ryzen 5 5600X + B450 + 32GB DDR4
- Runs 7B models great, 13B quantized
- Fine for voice commands and basic queries

**Flagship (~$4,000-5,400):**
- RTX 5090 32GB ($2,500-3,800)
- Ryzen 9 7950X + X670E + 128GB DDR5
- 70B models at high quality (20+ tok/s)
- 67% faster than 4090
- Future-proof for larger models

**Efficiency (Mac Mini M4 Pro, $1,399+):**
- 24-64GB unified memory
- 20W power draw vs 450W for 4090
- Great for always-on server
- Qwen 2.5 32B at 11-12 tok/s on 64GB config

---

## Software Stack

### Primary: Ollama

```bash
# Install (Linux)
curl -fsSL https://ollama.com/install.sh | sh

# Install (Windows)
# Download from https://ollama.com/download

# Pull models
ollama pull qwen2.5:7b        # Fast voice commands
ollama pull llama3.1:8b        # General chat
ollama pull qwen2.5:32b        # Complex reasoning (needs 24GB+ VRAM)
ollama pull llama3.1:70b-q4    # Near-cloud quality (needs 24GB VRAM)

# API runs on http://localhost:11434
```

**Why Ollama:**
- One-command install
- Built-in model library
- OpenAI-compatible API (works with LiteLLM, Open WebUI, HA)
- Auto-optimized for your hardware
- Dead simple

### Web Interface: Open WebUI

```bash
docker run -d -p 3000:8080 \
  -v open-webui:/app/backend/data \
  -e OLLAMA_BASE_URL=http://localhost:11434 \
  ghcr.io/open-webui/open-webui:main
```

- ChatGPT-like interface at `http://<server-ip>:3000`
- Model selection dropdown
- Conversation history
- RAG (Retrieval Augmented Generation) support
- User accounts

---

## Model Recommendations

### For Home Assistant Voice Commands (Speed Priority)

| Model | VRAM | Speed (4090) | Quality | Use Case |
|---|---|---|---|---|
| Qwen 2.5 7B | 4GB | 30+ tok/s | Good | Voice commands, HA control |
| Phi-3 Mini 3.8B | 2GB | 40+ tok/s | Decent | Ultra-fast simple queries |
| Llama 3.1 8B | 5GB | 30+ tok/s | Good | General chat |
| Gemma 2 9B | 6GB | 25+ tok/s | Good | Efficient general use |

### For Complex Reasoning (Quality Priority)

| Model | VRAM (Q4) | Speed (4090) | Quality | Use Case |
|---|---|---|---|---|
| Qwen 2.5 32B | 18GB | 15-20 tok/s | Very Good | Detailed analysis |
| Llama 3.1 70B | 35GB | 7-9 tok/s | Excellent | Near-cloud reasoning |
| DeepSeek R1 | Varies | 10-15 tok/s | Excellent | Step-by-step reasoning |
| Mistral 22B | 12GB | 20+ tok/s | Good | Balanced speed/quality |

### For Code

| Model | Best For |
|---|---|
| DeepSeek Coder V2 | Debugging, refactoring |
| Qwen3 Coder | Agentic coding tasks |
| Llama 3.1 70B | General code + reasoning |

### Quantization Guide

4-bit quantization maintains 95-98% quality at 75% less VRAM. Most users can't tell the difference.

| Quantization | VRAM Use | Quality | When to Use |
|---|---|---|---|
| Q4_K_M | 25% of full | 95-98% | Default for most models |
| Q5_K_M | 31% of full | 97-99% | When you have spare VRAM |
| Q8_0 | 50% of full | 99%+ | When quality matters most |
| FP16 (full) | 100% | 100% | Only for small models (7B) |

---

## RAM Requirements

| Model Size | Minimum System RAM | Recommended | GPU VRAM (Q4) |
|---|---|---|---|
| 7B | 16GB | 32GB | 4-5GB |
| 13B | 32GB | 32GB | 8-9GB |
| 30B | 32GB | 64GB | 16-18GB |
| 70B | 64GB | 128GB | 35-40GB |

---

## Power and Noise Considerations

This is an always-on server in your home:

| GPU | TDP | Idle Power | Annual Electricity (24/7) |
|---|---|---|---|
| RTX 3060 12GB | 170W | ~15W | ~$50-80/yr idle |
| RTX 4060 Ti 16GB | 165W | ~12W | ~$45-75/yr idle |
| RTX 4090 24GB | 450W | ~20W | ~$60-100/yr idle |
| RTX 5090 32GB | 575W | ~25W | ~$75-120/yr idle |

**Tips:**
- Configure GPU to idle at low power when no inference running
- Use Ollama's auto-unload (models unload from VRAM after idle timeout)
- Consider noise: a 4090 under load is not quiet. Use a case with good fans and put the server in a utility room/closet

---

## Server OS Recommendations

**Ubuntu Server 24.04 LTS** (recommended)
- Best NVIDIA driver support
- Docker native
- Easy Ollama install
- Headless (no GUI overhead)

**Windows 11** (if you want dual-use)
- Ollama has native Windows support
- Docker Desktop for Open WebUI
- More overhead than Linux

**Proxmox** (if you want to run multiple VMs/containers)
- GPU passthrough to LLM VM
- Run other services alongside
- More complex setup

---

## Sources

- https://localllm.in/blog/best-gpus-llm-inference-2025
- https://sanj.dev/post/affordable-ai-hardware-local-llms
- https://introl.com/blog/local-llm-hardware-pricing-guide-2025
- https://www.glukhov.org/post/2025/11/hosting-llms-ollama-localai-jan-lmstudio-vllm-comparison/
- https://huggingface.co/blog/daya-shankar/open-source-llms
