Question 1

Is the Arc B580 12GB or the RTX 5070 12GB better for local LLMs?

Accepted Answer

The RTX 5070 12GB has about 47% more memory bandwidth (672 vs 456 GB/s). Batch-1 decode tracks bandwidth closely, so a model that fits both cards should decode roughly 47% faster on the RTX 5070 12GB. Both fit the same number of catalog models at Q4/8K (18 of 61; 12 vs 12 GB VRAM). MSRP is $249 for the Arc B580 12GB vs $549 for the RTX 5070 12GB. MSRP is a launch list price, not live retail — Amazon prices move; click through for the current price.

Question 2

How much faster is the Arc B580 12GB than the RTX 5070 12GB for LLM inference?

Accepted Answer

On memory bandwidth the RTX 5070 12GB leads by about 47% (672 vs 456 GB/s), and batch-1 decode tracks bandwidth. In the Q4/8K head-to-head on this page, the Arc B580 12GB wins 0 of 40 shared model rows and the RTX 5070 12GB wins 40.

Question 3

Which can run larger models, the Arc B580 12GB or the RTX 5070 12GB?

Accepted Answer

Neither — both fit 18 of 61 catalog models at Q4/8K (12 vs 12 GB VRAM).

	Arc B580 12GB	RTX 5070 12GB
Vendor	Intel	NVIDIA
VRAM	12 GB	12 GB
Memory type	GDDR6	GDDR7
Memory bandwidth	456 GB/s	672 GB/s
TDP	190 W	250 W
MSRP (list)	$249	$549
Buy	Search Amazon (affiliate)	Search Amazon (affiliate)

Model	Params (B)	Arc B580 12GB tok/s	Arc B580 12GB fits	RTX 5070 12GB tok/s	RTX 5070 12GB fits	Winner
Qwen3-0.6B	0.8	362.7 est.	Yes	534.5 est.	Yes	RTX 5070 12GB
gemma-3-1b-it	1.0	290.2 est.	Yes	427.6 est.	Yes	RTX 5070 12GB
Llama-3.2-1B-Instruct	1.2	241.8 est.	Yes	356.4 est.	Yes	RTX 5070 12GB
gpt-oss-20b	21.5	180.6 est.	No	266.2 est.	No	RTX 5070 12GB
Qwen3-1.7B	2.0	145.1 est.	Yes	213.8 est.	Yes	RTX 5070 12GB
Qwen3-30B-A3B	30.5	117.8 est.	No	173.6 est.	No	RTX 5070 12GB
Qwen3-Coder-30B-A3B-Instruct	30.5	117.8 est.	No	173.6 est.	No	RTX 5070 12GB
Qwen3-30B-A3B-Instruct-2507	30.5	117.8 est.	No	173.6 est.	No	RTX 5070 12GB
GLM-4.7-Flash	31.2	113.1 est.	No	166.6 est.	No	RTX 5070 12GB
Llama-3.2-3B-Instruct	3.2	47.4 measured	Yes	133.6 est.	Yes	RTX 5070 12GB
Mistral-7B-Instruct-v0.3	7.2	40.3 est.	Yes	120.5 measured	Yes	RTX 5070 12GB
Phi-4-mini-instruct	3.8	76.4 est.	Yes	112.5 est.	Yes	RTX 5070 12GB
Phi-4-mini-reasoning	3.8	76.4 est.	Yes	112.5 est.	Yes	RTX 5070 12GB
gemma-3-4b-it	4.3	74.4 est.	Yes	109.7 est.	Yes	RTX 5070 12GB
Qwen3-4B-Instruct-2507	4.0	72.5 est.	Yes	106.9 est.	Yes	RTX 5070 12GB

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

Spec comparison

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

Fit coverage at Q4 / 8K

	Arc B580 12GB	RTX 5070 12GB
Catalog models that fit	18 of 61	18 of 61
Largest exclusive fit	—	—