Head to head · October 2026
RTX 3090 vs RTX 4090: which is better for local AI?
24GB against 24GB, 936 against 1,008 GB/s. What each runs, how fast, and which one to buy.
The verdict
Both have 24GB of memory, so they run the same models. The RTX 4090 generates text about 17% faster thanks to 1,008 GB/s of memory bandwidth versus 936 GB/s. The RTX 3090 costs about $1,450 less ($1,050 used vs $2,500 used).
- Get the RTX 3090 if you want the most for your money or you care about power draw, heat, and noise.
- Get the RTX 4090 if speed matters most.
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Performance
Model by model
Estimated single-user generation speed for popular models, at the best quantization each card can hold with 8K context.
| Model | RTX 3090 | RTX 4090 |
|---|---|---|
| Llama 3.1 8B Instruct | ~73 tok/sQ8_0 | ~86 tok/sQ8_0 |
| Qwen3 14B | ~41 tok/sQ8_0 | ~49 tok/sQ8_0 |
| gpt-oss-20b | ~120 tok/sMXFP4 | ~135 tok/sMXFP4 |
| Qwen3 30B-A3B (2507) | ~135 tok/sQ4_K_M | ~150 tok/sQ4_K_M |
| Gemma 3 27B | ~39 tok/sQ4_K_M | ~46 tok/sQ4_K_M |
| Qwen3 32B | ~41 tok/sQ3_K_M | ~48 tok/sQ3_K_M |
| Llama 3.3 70B Instruct | ~1.8 tok/sQ4_K_M Partial offload | ~1.8 tok/sQ4_K_M Partial offload |
| gpt-oss-120b | ~21 tok/sMXFP4 Partial offload | ~21 tok/sMXFP4 Partial offload |
Estimates from our bandwidth model; see methodology. Measured results, where we have them, are on each GPU's page.
Specifications
Spec by spec
| Spec | RTX 3090 | RTX 4090 |
|---|---|---|
| Memory | 24GB GDDR6X | 24GB GDDR6X |
| Bandwidth | 936 GB/s | 1,008 GB/s● |
| Power | 350W● | 450W |
| Price | ~$1,050 used● | ~$2,500 used |
| Price per GB | $44● | $104 |
| Architecture | Ampere | Ada Lovelace |
| Released | 2020 | 2022 |
| Software | CUDA, Vulkan | CUDA, Vulkan |
Our take
Bottom line on each
The default value pick for 24GB of CUDA memory and the backbone of most multi-GPU builds.
Still one of the fastest 24GB cards, though used prices now exceed its launch MSRP.
Frequently asked questions
Is the RTX 3090 or RTX 4090 better for running LLMs?
Both have 24GB of memory, so they run the same models. The RTX 4090 generates text about 17% faster thanks to 1,008 GB/s of memory bandwidth versus 936 GB/s. The RTX 3090 costs about $1,450 less ($1,050 used vs $2,500 used).
How much faster is the RTX 4090 than the RTX 3090 for AI?
About 17% faster at generating text in our estimates, because token generation is limited by memory bandwidth (1,008 GB/s vs 936 GB/s). Prompt processing depends more on compute and can differ by more.
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