Thurmon Demich Posted on May 30 • Originally published at bestgpuforllm.com Used RTX 3090 Buying Guide for Local LLM in 2026 # gpu # rtx3090 # used # llm Cross-posted from Best GPU for LLM — visit the original for our VRAM calculator, GPU comparison table, and current Amazon pricing. The RTX 3090 is three generations old, costs under $900 used, and still fits 34B models that a new $500 GPU cannot touch. For LLM inference, VRAM is the hard constraint — and 24GB at ~$850 is the best value on the market in 2026. But the used GPU market has landmines: mining-worn cards, dead VRAM chips, and sellers who know you can't easily tell the difference before you buy. This guide gives you the tools to buy one safely. See the recommended pick on the original guide Why 24GB still matters for LLM in 2026 VRAM is a filter, not a preference. A model either fits in VRAM or it doesn't — and the boundary between "fits" and "doesn't fit" falls squarely at the 24GB mark for 30B+ models. 7B models (Q4_K_M): need ~4.5GB — runs on almost anything 13B models (Q4_K_M): need ~8GB — fits an RTX 4060 Ti 8GB, barely 34B models (Q4_K_M): need ~20-22GB — requires 24GB VRAM 70B models (Q4_K_M): need ~40GB+ — requires dual 24GB cards or a 48GB workstation GPU For anyone running CodeLlama 34B, Qwen 2.5 32B, or Yi-34B locally, the RTX 3090 is the cheapest single GPU that actually fits the model. A new RTX 5070 Ti (16GB) cannot do it. A new RTX 5080 (16GB) cannot do it. The 3090's 24GB is the threshold card at the lowest price. On typical 34B Q4_K_M inference, community benchmarks show a 3090 producing roughly 12-18 tok/s — slow compared to the RTX 4090's 20-25 tok/s, but well above the ~8 tok/s threshold most people consider interactive. For a full speed breakdown, see RTX 4090 vs 3090 for LLM . VRAM chart available at the original article Price tiers: what to pay and what to avoid Price Signal Verdict Under $600 Too low — suspect dead VRAM, damaged card, or scam 🔴 Red flag $600–$699 Possible mini
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