Ryzen AI Max+ 395 128GB vs Arc B580 12GB for Local LLMs
The Arc B580 12GB has about 112% more memory bandwidth (456 vs 215 GB/s). Batch-1 decode tracks bandwidth closely, so a model that fits both cards should decode roughly 112% faster on the Arc B580 12GB. The Ryzen AI Max+ 395 128GB fits more of the catalog at Q4/8K — 51 vs 18 of 69 models (96 vs 12 GB VRAM). Largest model that fits the Ryzen AI Max+ 395 128GB but not the Arc B580 12GB: DeepSeek-V4-Flash (158.1B). MSRP is $2,000 for the Ryzen AI Max+ 395 128GB 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 (41 shared models), the Arc B580 12GB posts the higher tok/s in 39 rows vs 2. Methodology.