Can I run Ornith-1.5-9B on an RTX 5090?

Yes

Its published weights (19.3 GB) fit in the 28.8 GB an RTX 5090 can use, with room for ≈ 256K tokens of context.

Full analysis of Ornith-1.5-9B Everything that runs on RTX 5090 Get the weights on Hugging Face

hf download ornith-ai/Ornith-1.5-9B

Files and context on RTX 5090

Each file of Ornith-1.5-9B (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	19.3 GB	Fits	256K	256K
BF16ornith-ai/Ornith-1.5-9B-GGUF	18.4 GB	Fits	256K	256K
Q8_0ornith-ai/Ornith-1.5-9B-GGUF	9.79 GB	Fits	256K	256K
Q6_Kornith-ai/Ornith-1.5-9B-GGUF	7.56 GB	Fits	256K	256K
Q5_K_Mornith-ai/Ornith-1.5-9B-GGUF	6.64 GB	Fits	256K	256K
Q4_K_Mornith-ai/Ornith-1.5-9B-GGUF	5.78 GB	Fits	256K	256K

Ornith-1.5-9B on other hardware

Popular models that run on RTX 5090

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.