The Arc B580 12GB has about 280% more memory bandwidth (456 vs 120 GB/s). Batch-1 decode tracks bandwidth closely, so a model that fits both cards should decode roughly 280% faster on the Arc B580 12GB. The Mac mini M4 32GB fits more of the catalog at Q4/8K — 38 vs 18 of 61 models (32 vs 12 GB VRAM). Largest model that fits the Mac mini M4 32GB but not the Arc B580 12GB: Mixtral-8x7B-Instruct-v0.1 (46.7B). MSRP is $249 for the Arc B580 12GB vs $999 for the Mac mini M4 32GB. 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 Arc B580 12GB posts the higher tok/s in 38 rows vs 2. Methodology.