Can I Run InternLM 3 20B Instruct on NVIDIA GeForce RTX 5080?
Written by Jakub Rusinowski · Last updated September 29, 2026
Yes, but it's tight. InternLM 3 20B Instruct needs 14.5 GB at 8K context (12.1 GB weights + 2.4 GB KV cache/overhead) at Q4_K_M and the NVIDIA GeForce RTX 5080 has 16 GB, leaving about 1.5 GB of headroom, at roughly 56 tok/s (estimated) with room for up to 8K of context.
See what else this hardware can run →
The numbers
| Model | InternLM 3 20B Instruct |
| Parameters | 20B |
| Quantization | Q4_K_M |
| VRAM needed (8K context) | 14.5 GB |
| NVIDIA GeForce RTX 5080 VRAM | 16 GB |
| Verdict | Runs |
| Max context | 8K |
| Estimated speed | ~56 tok/s |
InternLM 3 20B Instruct on the NVIDIA GeForce RTX 5080: VRAM by quantization
| Quant | VRAM needed | Fits 16 GB? | Max context | Whole PC |
|---|---|---|---|---|
| F16 | 42.4 GB | ✗ No | — | — |
| Q8_0 | 23.6 GB | ✗ No | — | Build for this |
| Q6_K | 18.8 GB | ✗ No | — | — |
| Q5_K_M | 16.6 GB | ✗ No | — | — |
| Q4_K_M | 14.5 GB | ✓ Yes | 8K | Build for this |
| Q3_K_M | 10.9 GB | ✓ Yes | 32K | — |
| Q2_K | 9 GB | ✓ Yes | 32K | — |
Assumes an 8K-token context with an f16 KV cache, on an estimated architecture — this model publishes no config we can read. A longer window needs more; a quantized KV cache needs less. “Max context” is the largest window that still fits in 16 GB. Figures are estimates from parameter count, quantization and memory bandwidth — the analyzer lets you tune KV-cache quant and context.
Context costs VRAM too. At Q4_K_M on the NVIDIA GeForce RTX 5080: 8K 14.5 GB · 32K 19.2 GB ✗. Past 32K it no longer fits 16 GB — a q8_0 KV cache buys roughly half of that back, which the calculator will price for you.
What to do next
Nothing to change — run it at Q4_K_M. If you want more capability, check whether the next size up also fits.
No compatible GPU? InternLM 3 20B Instruct on 24 GB of system RAM, CPU only: runs.
Running InternLM 3 20B Instruct on this card:
At 2 hrs/day, buying (~$999) beats renting at $0.34/hr after about 4.1 years.
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Cloud rates verified 2026-07 — estimates, and marketplace prices vary. Buying price is GPU MSRP only, not a full PC.
Other InternLM 3 sizes on the NVIDIA GeForce RTX 5080
- InternLM 3 8B Instruct — runs (6.5 GB)
InternLM 3 20B Instruct on nearby hardware
- Intel Arc B580 (12 GB) — runs at a lower quant
- AMD Radeon RX 7900 XT (20 GB) — runs
All InternLM 3 sizes on the NVIDIA GeForce RTX 5080 | InternLM 3 20B Instruct model page | NVIDIA GeForce RTX 5080 GPU page | VRAM calculator | Check your hardware