The Arc B580 12GB has about 2% more memory bandwidth (456 vs 448 GB/s). Batch-1 decode tracks bandwidth closely, so a model that fits both cards should decode roughly 2% faster on the Arc B580 12GB. The RTX 5060 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 5060 Ti 16GB but not the Arc B580 12GB: gpt-oss-20b (21.5B). MSRP is $249 for the Arc B580 12GB vs $429 for the RTX 5060 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 Arc B580 12GB posts the higher tok/s in 22 rows vs 18. Methodology.