RTX A6000 48GB vs Arc B580 12GB for Local LLMs

The RTX A6000 48GB has about 68% more memory bandwidth (768 vs 456 GB/s). Batch-1 decode tracks bandwidth closely, so a model that fits both cards should decode roughly 68% faster on the RTX A6000 48GB. The RTX A6000 48GB fits more of the catalog at Q4/8K — 39 vs 18 of 61 models (48 vs 12 GB VRAM). Largest model that fits the RTX A6000 48GB but not the Arc B580 12GB: Qwen3-Coder-Next (79.7B). MSRP is $4,500 for the RTX A6000 48GB vs $249 for the Arc B580 12GB. 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 A6000 48GB posts the higher tok/s in 33 rows vs 7. Methodology.

Spec comparison

	RTX A6000 48GB	Arc B580 12GB
Vendor	NVIDIA	Intel
VRAM	48 GB	12 GB
Memory type	GDDR6	GDDR6
Memory bandwidth	768 GB/s	456 GB/s
TDP	300 W	190 W
MSRP (list)	$4,500	$249
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)	RTX A6000 48GB tok/s	RTX A6000 48GB fits	Arc B580 12GB tok/s	Arc B580 12GB fits	Winner
Qwen3-0.6B	0.8	610.9 est.	Yes	362.7 est.	Yes	RTX A6000 48GB
Qwen3-Next-80B-A3B-Instruct	81.3	499.8 est.	No	18.5 est.	No	RTX A6000 48GB
gemma-3-1b-it	1.0	488.7 est.	Yes	290.2 est.	Yes	RTX A6000 48GB
Llama-3.2-1B-Instruct	1.2	407.3 est.	Yes	241.8 est.	Yes	RTX A6000 48GB
Qwen3-1.7B	2.0	244.4 est.	Yes	145.1 est.	Yes	RTX A6000 48GB
gpt-oss-20b	21.5	135.8 est.	Yes	180.6 est.	No	Arc B580 12GB
Qwen3-30B-A3B	30.5	162.9 est.	Yes	117.8 est.	No	RTX A6000 48GB
Qwen3-Coder-30B-A3B-Instruct	30.5	162.9 est.	Yes	117.8 est.	No	RTX A6000 48GB
GLM-4.7-Flash	31.2	162.9 est.	Yes	113.1 est.	No	RTX A6000 48GB
Qwen3-30B-A3B-Instruct-2507	30.5	162.9 est.	Yes	117.8 est.	No	RTX A6000 48GB
Qwen3-Coder-Next	79.7	162.9 est.	Yes	19.3 est.	No	RTX A6000 48GB
Llama-3.2-3B-Instruct	3.2	152.7 est.	Yes	47.4 measured	Yes	RTX A6000 48GB
Phi-4-mini-instruct	3.8	128.6 est.	Yes	76.4 est.	Yes	RTX A6000 48GB
Phi-4-mini-reasoning	3.8	128.6 est.	Yes	76.4 est.	Yes	RTX A6000 48GB
gemma-3-4b-it	4.3	125.3 est.	Yes	74.4 est.	Yes	RTX A6000 48GB

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

	RTX A6000 48GB	Arc B580 12GB
Catalog models that fit	39 of 61	18 of 61
Largest exclusive fit	Qwen3-Coder-Next (79.7B)	—

RTX A6000 48GB details → · Arc B580 12GB details →