Can I run Qwen3-8B-MLX-4bit on an RTX 5090?

Yes

Its published weights (4.35 GB) fit in the 28.8 GB an RTX 5090 can use, with room for ≈ 40K tokens of context.

Full analysis of Qwen3-8B-MLX-4bit Everything that runs on RTX 5090 Get the weights on Hugging Face

hf download Qwen/Qwen3-8B-MLX-4bit

Files and context on RTX 5090

Each file of Qwen3-8B-MLX-4bit (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.

File	Size	On RTX 5090	Context (16-bit)	Context (8-bit)
As published	4.35 GB	Fits	40K	40K

Qwen3-8B-MLX-4bit on other hardware

NVIDIA H100Yes
RTX 5090Yes
RTX 4090Yes
RTX 3090Yes
RTX 5060 Ti 16 GBYes
RTX 3060 12 GBYes
RTX 4060Yes
Mac with 32 GBYes
Mac with 64 GBYes
Mac with 128 GBYes

Popular models that run on RTX 5090

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Qwen2.5-7B-InstructQwen · 7.62B
Qwen3.5-9BQwen · 9.65B
Qwen2.5-0.5B-InstructQwen · 494M

Assumes 90% of the card's memory is usable and at least 4K tokens of context for one conversation, with the context cache in 16-bit unless noted. Fits leaves at least 20% of that memory for context; Tight leaves less.