Arc B580 12GB vs RTX 5070 Ti 16GB for Local LLMs

The RTX 5070 Ti 16GB has about 96% more memory bandwidth (896 vs 456 GB/s). Batch-1 decode tracks bandwidth closely, so a model that fits both cards should decode roughly 96% faster on the RTX 5070 Ti 16GB. The RTX 5070 Ti 16GB fits more of the catalog at Q4/8K — 25 vs 18 of 61 models (16 vs 12 GB VRAM). Largest model that fits the RTX 5070 Ti 16GB but not the Arc B580 12GB: gpt-oss-20b (21.5B). MSRP is $249 for the Arc B580 12GB vs $749 for the RTX 5070 Ti 16GB. 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 5070 Ti 16GB posts the higher tok/s in 34 rows vs 6. Methodology.

Spec comparison

	Arc B580 12GB	RTX 5070 Ti 16GB
Vendor	Intel	NVIDIA
VRAM	12 GB	16 GB
Memory type	GDDR6	GDDR7
Memory bandwidth	456 GB/s	896 GB/s
TDP	190 W	300 W
MSRP (list)	$249	$749
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 5070 Ti 16GB tok/s	RTX 5070 Ti 16GB fits	Winner
Qwen3-0.6B	0.8	362.7 est.	Yes	712.7 est.	Yes	RTX 5070 Ti 16GB
gemma-3-1b-it	1.0	290.2 est.	Yes	570.2 est.	Yes	RTX 5070 Ti 16GB
Llama-3.2-1B-Instruct	1.2	241.8 est.	Yes	475.2 est.	Yes	RTX 5070 Ti 16GB
Qwen3-30B-A3B	30.5	117.8 est.	No	411.5 est.	No	RTX 5070 Ti 16GB
Qwen3-Coder-30B-A3B-Instruct	30.5	117.8 est.	No	411.5 est.	No	RTX 5070 Ti 16GB
Qwen3-30B-A3B-Instruct-2507	30.5	117.8 est.	No	411.5 est.	No	RTX 5070 Ti 16GB
GLM-4.7-Flash	31.2	113.1 est.	No	395.0 est.	No	RTX 5070 Ti 16GB
Qwen3-1.7B	2.0	145.1 est.	Yes	285.1 est.	Yes	RTX 5070 Ti 16GB
gpt-oss-20b	21.5	180.6 est.	No	189.5 measured	Yes	RTX 5070 Ti 16GB
Llama-3.2-3B-Instruct	3.2	47.4 measured	Yes	178.2 est.	Yes	RTX 5070 Ti 16GB
Mistral-7B-Instruct-v0.3	7.2	40.3 est.	Yes	160.2 measured	Yes	RTX 5070 Ti 16GB
Phi-4-mini-instruct	3.8	76.4 est.	Yes	150.0 est.	Yes	RTX 5070 Ti 16GB
Phi-4-mini-reasoning	3.8	76.4 est.	Yes	150.0 est.	Yes	RTX 5070 Ti 16GB
gemma-3-4b-it	4.3	74.4 est.	Yes	146.2 est.	Yes	RTX 5070 Ti 16GB
Qwen3-4B-Instruct-2507	4.0	72.5 est.	Yes	142.5 est.	Yes	RTX 5070 Ti 16GB

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 5070 Ti 16GB
Catalog models that fit	18 of 61	25 of 61
Largest exclusive fit	—	gpt-oss-20b (21.5B)

Arc B580 12GB details → · RTX 5070 Ti 16GB details →