What PC Specs Do You Need for a Local LLM? VRAM, GPU & Memory Guide [2026]
A beginner-friendly guide to the PC specs you need to run a local LLM. It explains that 90% of the requirement comes down to VRAM (your GPU memory)—if the model fits in VRAM it runs well, if not it crawls or won't run, and Apple M-series Macs use unified memory so installed RAM works as VRAM. It covers quantization basics (FP16 ~2 bytes/param, Q8 ~1 byte = half, Q4 ~0.5–0.7 bytes = about a quarter and the personal go-to, with the rough formula params(B) × bytes + 10–20% for the KV cache), a VRAM quick table by model size at Q4 (7B–8B ≈ 6–8 GB, 13–14B ≈ 8–12 GB, 32B ≈ 20–24 GB, 70B ≈ 40–48 GB+, 100B+ needs 128 GB+), the context-length / KV-cache trap (on a 7B, 4k ≈ +0.3 GB, 32k ≈ +2.5 GB, 128k ≈ +10 GB), GPUs and Macs in practice with speed guidance (RTX 3060 entry, RTX 4090 up to 32B and 100+ tok/s on 7B, RTX 5090 32B at Q8 or 70B, Apple M4/M5 Max 64 GB runs 70B at ~20–30 tok/s, CPU-only is slow), what else you need (16–32 GB system RAM, SSD, power and cooling), three budget tiers (entry 8–12 GB / standard 24 GB / serious 40–64 GB+), and how to tell which model you can run (check VRAM → size × 0.6 + context → does it fit), based on 2026 information.