Arc B580 12GB vs RTX 3070 8GB for Local LLMs

The Arc B580 12GB has about 2% more memory bandwidth (456 vs 448 GB/s). Batch-1 decode tracks bandwidth closely, so a model that fits both cards should decode roughly 2% faster on the Arc B580 12GB. The Arc B580 12GB fits more of the catalog at Q4/8K — 18 vs 17 of 61 models (12 vs 8 GB VRAM). Largest model that fits the Arc B580 12GB but not the RTX 3070 8GB: gemma-3-12b-it (12.2B). MSRP is $249 for the Arc B580 12GB vs $499 for the RTX 3070 8GB. 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 (38 shared models), the Arc B580 12GB posts the higher tok/s in 36 rows vs 2. Methodology.

Spec comparison

	Arc B580 12GB	RTX 3070 8GB
Vendor	Intel	NVIDIA
VRAM	12 GB	8 GB
Memory type	GDDR6	GDDR6
Memory bandwidth	456 GB/s	448 GB/s
TDP	190 W	220 W
MSRP (list)	$249	$499
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 38 shared models

Model	Params (B)	Arc B580 12GB tok/s	Arc B580 12GB fits	RTX 3070 8GB tok/s	RTX 3070 8GB fits	Winner
Qwen3-0.6B	0.8	362.7 est.	Yes	356.4 est.	Yes	Arc B580 12GB
gemma-3-1b-it	1.0	290.2 est.	Yes	285.1 est.	Yes	Arc B580 12GB
Llama-3.2-1B-Instruct	1.2	241.8 est.	Yes	237.6 est.	Yes	Arc B580 12GB
gpt-oss-20b	21.5	180.6 est.	No	78.9 est.	No	Arc B580 12GB
Qwen3-1.7B	2.0	145.1 est.	Yes	142.5 est.	Yes	Arc B580 12GB
Qwen3-30B-A3B	30.5	117.8 est.	No	51.4 est.	No	Arc B580 12GB
Qwen3-Coder-30B-A3B-Instruct	30.5	117.8 est.	No	51.4 est.	No	Arc B580 12GB
Qwen3-30B-A3B-Instruct-2507	30.5	117.8 est.	No	51.4 est.	No	Arc B580 12GB
GLM-4.7-Flash	31.2	113.1 est.	No	49.4 est.	No	Arc B580 12GB
Llama-3.2-3B-Instruct	3.2	47.4 measured	Yes	89.1 est.	Yes	RTX 3070 8GB
Phi-4-mini-instruct	3.8	76.4 est.	Yes	75.0 est.	Yes	Arc B580 12GB
Phi-4-mini-reasoning	3.8	76.4 est.	Yes	75.0 est.	Yes	Arc B580 12GB
gemma-3-4b-it	4.3	74.4 est.	Yes	73.1 est.	Yes	Arc B580 12GB
Qwen3-4B-Instruct-2507	4.0	72.5 est.	Yes	71.3 est.	Yes	Arc B580 12GB
Qwen3-4B-Thinking-2507	4.0	72.5 est.	Yes	71.3 est.	Yes	Arc B580 12GB

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 3070 8GB
Catalog models that fit	18 of 61	17 of 61
Largest exclusive fit	gemma-3-12b-it (12.2B)	—

Arc B580 12GB details → · RTX 3070 8GB details →