Arc B580 12GB vs MI300X 192GB for Local LLMs

The MI300X 192GB has about 1062% more memory bandwidth (5,300 vs 456 GB/s). Batch-1 decode tracks bandwidth closely, so a model that fits both cards should decode roughly 1062% faster on the MI300X 192GB. The MI300X 192GB fits more of the catalog at Q4/8K — 50 vs 18 of 61 models (192 vs 12 GB VRAM). Largest model that fits the MI300X 192GB but not the Arc B580 12GB: Qwen3-235B-A22B (235.1B). MSRP is $249 for the Arc B580 12GB vs $15,000 for the MI300X 192GB. MSRP is a launch list price, not live retail — Amazon prices move; click through for the current price. Not retail-shoppable: MI300X 192GB (datacenter-class; cloud rental is the realistic way to use it). In the Q4/8K head-to-head below (40 shared models), the MI300X 192GB posts the higher tok/s in 40 rows vs 0. Methodology.

Spec comparison

	Arc B580 12GB	MI300X 192GB
Vendor	Intel	AMD
VRAM	12 GB	192 GB
Memory type	GDDR6	HBM3
Memory bandwidth	456 GB/s	5,300 GB/s
TDP	190 W	750 W
MSRP (list)	$249	$15,000
Buy	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	MI300X 192GB tok/s	MI300X 192GB fits	Winner
Qwen3-0.6B	0.8	362.7 est.	Yes	4215.9 est.	Yes	MI300X 192GB
gemma-3-1b-it	1.0	290.2 est.	Yes	3372.7 est.	Yes	MI300X 192GB
Llama-3.2-1B-Instruct	1.2	241.8 est.	Yes	2810.6 est.	Yes	MI300X 192GB
Qwen3-1.7B	2.0	145.1 est.	Yes	1686.4 est.	Yes	MI300X 192GB
Qwen3-30B-A3B	30.5	117.8 est.	No	1124.2 est.	Yes	MI300X 192GB
Qwen3-Coder-30B-A3B-Instruct	30.5	117.8 est.	No	1124.2 est.	Yes	MI300X 192GB
GLM-4.7-Flash	31.2	113.1 est.	No	1124.2 est.	Yes	MI300X 192GB
Qwen3-30B-A3B-Instruct-2507	30.5	117.8 est.	No	1124.2 est.	Yes	MI300X 192GB
Qwen3-Next-80B-A3B-Instruct	81.3	18.5 est.	No	1124.2 est.	Yes	MI300X 192GB
Qwen3-Coder-Next	79.7	19.3 est.	No	1124.2 est.	Yes	MI300X 192GB
Llama-3.2-3B-Instruct	3.2	47.4 measured	Yes	1054.0 est.	Yes	MI300X 192GB
gpt-oss-20b	21.5	180.6 est.	No	936.9 est.	Yes	MI300X 192GB
Phi-4-mini-instruct	3.8	76.4 est.	Yes	887.6 est.	Yes	MI300X 192GB
Phi-4-mini-reasoning	3.8	76.4 est.	Yes	887.6 est.	Yes	MI300X 192GB
gemma-3-4b-it	4.3	74.4 est.	Yes	864.8 est.	Yes	MI300X 192GB

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	MI300X 192GB
Catalog models that fit	18 of 61	50 of 61
Largest exclusive fit	—	Qwen3-235B-A22B (235.1B)

Arc B580 12GB details → · MI300X 192GB details →