Can I run Qwen3-4B on an RTX 4090?
Yes
Its published weights (8.04 GB) fit in the 21.6 GB an RTX 4090 can use, with room for ≈ 40K tokens of context.
hf download Qwen/Qwen3-4BFiles and context on RTX 4090
Each file of Qwen3-4B (and of GGUF versions the site has analyzed), and how much context fits next to it, with the context cache in 16-bit or 8-bit.