$3,842

| Category | Component | Price | Rationale | Buy |
|---|---|---|---|---|
| gpu | 2x NVIDIA GeForce RTX 3090 24GB (Used) + NVLink Bridge | $1,679 | 48GB total VRAM via dual 3090s with NVLink — the only consumer config that runs 70B models without CPU offloading. NVLink bridge (~$80) gives combined 1872 GB/s bandwidth across both cards. Used 3090 pairs go for $700-800 each. This is half the cost of a single RTX 4090 while delivering 2x the VRAM. TDP is 700W combined — serious power draw, but the 70B capability is worth it for a household AI server. Source: r/LocalLLaMA dual-3090 benchmark threads. | Buy |
| cpu | $349 | 12-core at 65W TDP. Handles concurrent model serving, RAG indexing, embedding generation, and system tasks without breaking a sweat. The non-X variant saves 50W under load vs the 7900X — meaningful for 24/7 operation. 12 cores ensure no request queuing under multi-user load. | Buy | |
| motherboard | $349 | X670E with dual PCIe x16 slots — mandatory for dual GPUs. 10GbE LAN for high-bandwidth serving across the network. Thunderbolt 4 for direct-attach storage expansion. 4 M.2 slots and 4 SATA ports for hybrid NAS storage. | Buy | |
| ram | 128GB DDR5-5600 (4x32GB) | $319 | 128GB is not overkill for a multi-user 70B server: Ollama caches the full model in system RAM for fast reload (~40GB for 70B Q3), Open WebUI + vector DB consume 4-8GB, and the OS + services need headroom. Four DIMM slots populated for maximum memory bandwidth to feed dual GPUs during CPU-offload scenarios. | Buy |
| storage | $559 | 2TB NVMe holds the OS and 30+ quantized models for instant serving. 4x 4TB IronWolf in RAID 10 provides 8TB usable NAS storage with both redundancy and read performance. IronWolf rated for 24/7 NAS workloads. This configuration survives a single drive failure without data loss. | Buy | |
| psu | $259 | 1200W for dual 3090s (700W combined GPU TDP) plus system. Platinum efficiency reduces waste heat — critical in an enclosed server environment. At typical 850W load, the PSU runs at peak efficiency. Digital monitoring via Corsair iCUE for power tracking. | Buy | |
| case | Fractal DesignFractal Design Define 7 XL | $219 | Full tower with 18 HDD positions for massive NAS expansion. Sound-dampened panels for quiet server operation. Fits dual 3090s (491mm GPU clearance). Removable top panel and modular interior for easy maintenance. The Define series is the go-to for silent servers. | Buy |
| cooler | NoctuaNoctua NH-D15 chromax.black | $109 | Premium dual-tower cooler for the 12-core 7900. Even at 65W TDP, the server runs 24/7 and thermals compound in a closed case. The D15 keeps the 7900 at 55C under sustained load with fans at 800 RPM — near-silent. No pump failure risk vs AIO, which matters for an always-on server. | Buy |
| Total | $3,842 | |||
Search links — prices and availability vary by retailer.
Prices and availability vary. Inspect hardware before purchasing.
AI models tested on this build's hardware.
| Model | Quant | Speed |
|---|---|---|
| Llama 3.3 70B Instruct | Q3_K_M | 15 tok/s |
| Llama 3.1 70B Instruct | Q3_K_M | 14 tok/s |
| Qwen 2.5 72B Instruct | Q3_K_M | 14 tok/s |
| Qwen 2.5 Coder 32B Instruct | Q5_K_M | 28 tok/s |
| QwQ 32B Preview | Q5_K_M | 27 tok/s |
| DeepSeek R1 Distill Qwen 32B | Q5_K_M | 26 tok/s |
| Mixtral 8x7B Instruct | Q4_K_M | 40 tok/s |
| Llama 3.1 8B Instruct | Q8_0 | 85 tok/s |
| Gemma 2 27B Instruct | Q5_K_M | 25 tok/s |
| nomic-embed-text v1.5 | FP16 | — |
| Whisper Large V3 | FP16 | — |
| FLUX.1 Dev | FP16 | — |
Always-on local AI server for a household or small team. Runs Ollama + Open WebUI accessible from any device on the network. Serves chat, coding assistance, document Q&A, and transcription to multiple simultaneous users — with zero API costs and complete data privacy.
7 GB of 48 GB
41 GB headroom for additional workloads
If you're paying ~$80/month for cloud API access, this build pays for itself in 10 months.
Based on a 3-person household using ChatGPT Plus ($20/mo each = $60/mo) plus occasional API calls for document processing (~$20/mo). Budget Home AI Server at $1,162 including electricity (~$15/mo for the budget tier at 250W average). Break-even includes electricity. After break-even, savings are $65+/month indefinitely. Privacy benefit: no family conversations, documents, or voice recordings leave your network.
Swap to dual RTX 4090 (48GB, faster per-card) when budget allows — requires the same motherboard and PSU. Or add a 10GbE switch and second server node for redundancy. Storage can expand to 18 drives in this case for 72TB+ raw capacity. For 120B+ models, consider moving to used A6000 48GB cards ($2500 each, single card runs 70B at Q4).
Last updated: 2026-03-14.