NVIDIA · 24 GB GDDR6X · 936 GB/s bandwidth ·
Meta · 8.0B · model ctx up to 128K
Yes — the RTX 3090 24GB (24 GB GDDR6X) can run Llama-3.1-8B-Instruct. At Q4 with the default 8K context it needs ≈ 7.0 GB VRAM (weights 4.4 GB + KV cache 1.6 GB + 1 GB runtime overhead), which fits within 24 GB. Decode at Q4/8K: ≈ 62.0 tok/s (measured, batch 1). FP16 (≈ 18.6 GB) also fits, at ≈ 20.5 tok/s (estimated). Estimates come from memory-bandwidth math; rows tagged measured override estimates. Relative ranking is more reliable than absolute tok/s. Methodology.
Fit & speed by quant and context
Quant
Context
VRAM needed
Fits?
tok/s (decode)
Q4
4K
6.2 GB
Yes
62.0measured
Q4
8K default
7.0 GB
Yes
62.0measured
Q4
32K
11.8 GB
Yes
62.0measured
FP16
4K
17.8 GB
Yes
20.5est.
FP16
8K default
18.6 GB
Yes
20.5est.
FP16
32K
23.4 GB
No
61.5est.
Fits = weights + KV(ctx) + 1 GB overhead ≤ 95% of VRAM. Measured
anchors are context-agnostic; the fit verdict is recomputed per context. A missing tok/s
means the model is far beyond this card (offload-only territory).