Arc B580 12GB vs RTX 3090 Ti 24GB for Local LLMs

The RTX 3090 Ti 24GB has about 121% more memory bandwidth (1,008 vs 456 GB/s). Batch-1 decode tracks bandwidth closely, so a model that fits both cards should decode roughly 121% faster on the RTX 3090 Ti 24GB. The RTX 3090 Ti 24GB fits more of the catalog at Q4/8K — 33 vs 18 of 61 models (24 vs 12 GB VRAM). Largest model that fits the RTX 3090 Ti 24GB but not the Arc B580 12GB: GLM-4.7-Flash (31.2B). MSRP is $249 for the Arc B580 12GB vs $1,999 for the RTX 3090 Ti 24GB. MSRP is a launch list price, not live retail — Amazon prices move; click through for the current price. In the Q4/8K head-to-head below (40 shared models), the RTX 3090 Ti 24GB posts the higher tok/s in 33 rows vs 7. Methodology.

Spec comparison

	Arc B580 12GB	RTX 3090 Ti 24GB
Vendor	Intel	NVIDIA
VRAM	12 GB	24 GB
Memory type	GDDR6	GDDR6X
Memory bandwidth	456 GB/s	1,008 GB/s
TDP	190 W	450 W
MSRP (list)	$249	$1,999
Buy	Search Amazon (affiliate)	Search Amazon (affiliate)

MSRP is the launch list price, not live retail. Buy links are Amazon affiliate links — the price after you click is the live price.

Q4 / 8K head-to-head — top 15 of 40 shared models

Model	Params (B)	Arc B580 12GB tok/s	Arc B580 12GB fits	RTX 3090 Ti 24GB tok/s	RTX 3090 Ti 24GB fits	Winner
Qwen3-0.6B	0.8	362.7 est.	Yes	801.8 est.	Yes	RTX 3090 Ti 24GB
gemma-3-1b-it	1.0	290.2 est.	Yes	641.5 est.	Yes	RTX 3090 Ti 24GB
Llama-3.2-1B-Instruct	1.2	241.8 est.	Yes	534.5 est.	Yes	RTX 3090 Ti 24GB
Qwen3-1.7B	2.0	145.1 est.	Yes	320.7 est.	Yes	RTX 3090 Ti 24GB
Qwen3-30B-A3B	30.5	117.8 est.	No	213.8 est.	Yes	RTX 3090 Ti 24GB
Qwen3-Coder-30B-A3B-Instruct	30.5	117.8 est.	No	213.8 est.	Yes	RTX 3090 Ti 24GB
GLM-4.7-Flash	31.2	113.1 est.	No	213.8 est.	Yes	RTX 3090 Ti 24GB
Qwen3-30B-A3B-Instruct-2507	30.5	117.8 est.	No	213.8 est.	Yes	RTX 3090 Ti 24GB
Llama-3.2-3B-Instruct	3.2	47.4 measured	Yes	200.5 est.	Yes	RTX 3090 Ti 24GB
gpt-oss-20b	21.5	180.6 est.	No	178.2 est.	Yes	Arc B580 12GB
Qwen3-Coder-Next	79.7	19.3 est.	No	170.4 est.	No	RTX 3090 Ti 24GB
Phi-4-mini-instruct	3.8	76.4 est.	Yes	168.8 est.	Yes	RTX 3090 Ti 24GB
Phi-4-mini-reasoning	3.8	76.4 est.	Yes	168.8 est.	Yes	RTX 3090 Ti 24GB
gemma-3-4b-it	4.3	74.4 est.	Yes	164.5 est.	Yes	RTX 3090 Ti 24GB
Qwen3-Next-80B-A3B-Instruct	81.3	18.5 est.	No	164.0 est.	No	RTX 3090 Ti 24GB

est. = bandwidth-based estimate; measured = curated real benchmark that overrides the estimate. Fits = weights + KV(8K) + 1 GB overhead ≤ 95% of VRAM.

Fit coverage at Q4 / 8K

	Arc B580 12GB	RTX 3090 Ti 24GB
Catalog models that fit	18 of 61	33 of 61
Largest exclusive fit	—	GLM-4.7-Flash (31.2B)

Arc B580 12GB details → · RTX 3090 Ti 24GB details →